http://hdl.handle.net/1811/6635 2013-06-19T10:59:18Z 2013-06-19T10:59:18Z Morgan, Philip J. Fleisher, Adam J. Roscioli, Joseph R. Pratt, David W. http://hdl.handle.net/1811/38405 2009-07-30T06:19:10Z 2009-01-01T00:00:00Z

HIGH RESOLUTION ELECTRONIC SPECTROSCOPY OF THE ARGON VAN DER WAALS COMPLEXES OF 1, 2, 3, 6, 7, 8-HEXAHYDROPYRENE IN THE GAS PHASE. Morgan, Philip J.; Fleisher, Adam J.; Roscioli, Joseph R.; Pratt, David W. The study of van der Waals complexes provides structural and dynamical information about the weak chemical forces that exist between aromatic molecules and rare gas atoms. In this report, we describe the rotationally resolved fluorescence excitation spectra of the S$_1$$\leftarrow$S$_0$ origin bands of the single argon atom complexes of 1, 2, 3, 6, 7, 8-hexahydropyrene. Analysis of the spectra provides information about the geometries of both conformers of the bare molecule and their argon complexes in both electronic states. The equilibrium positions of the argon atom in both conformers will be discussed. Work supported by NSF (CHE-0615755); Author Institution: Department of Chemistry, University of Pittsburgh, PA 15260

2009-01-01T00:00:00Z Morgan, Philip J. Fleisher, Adam J. Roscioli, Joseph R. Pratt, David W. Dijk, Cody Van Nest, Samantha Van Chen, Ziqiu Wijngaarden, Jennifer Van http://hdl.handle.net/1811/38404 2012-12-29T07:41:23Z 2009-01-01T00:00:00Z

HIGH RESOLUTION INVESTIGATION OF SILACYCLOBUTANE USING FTMW AND SYNCHROTRON BASED FTIR SPECTROSCOPY Dijk, Cody Van; Nest, Samantha Van; Chen, Ziqiu; Wijngaarden, Jennifer Van The rotational spectrum of silacyclobutane (c-C${_3}$H${_8}$Si) has been measured between 8 and 24 GHz using Fourier transform microwave spectroscopy. Although the microwave spectrum was previously reported \underline{\textbf{54}} (4979), 1971.}, the current study is the first observation of tunneling splitting in the ground state due to ring puckering. The observed transitions within each tunneling state obey \textit{a-}type selection rules and \textit{c-}type transitions that connect the inversion states have also been observed. The rotational constants determined were used to model the rotational structure of several vibrational bands of silacyclobutane including the weak ring puckering mode at 157 cm$^{-1}$. The far infared spectrum of silacyclobutane was recorded using the far infrared beamline at the Canadian Light Source and includes multiple tunneling doubled bands. The ongoing analysis of the incredibly rich vibrational spectrum of silacyclobutane will be discussed. W. C. Pringle \textit{J. Chem. Phys.; Author Institution: Department of Chemistry, University of Manitoba, Winnipeg MB R3T 2N2 Canada

2009-01-01T00:00:00Z Dijk, Cody Van Nest, Samantha Van Chen, Ziqiu Wijngaarden, Jennifer Van Ernst, Wolfgang E. http://hdl.handle.net/1811/38403 2009-07-30T06:19:07Z 2009-01-01T00:00:00Z

HELIUM DROPLETS AS NANO-CRYOSTATS FOR MOLECULAR SPECTROSCOPY: AGGREGATION, STATE SELECTION AND ELECTRON SPIN RESONANCE Ernst, Wolfgang E. Droplets of about $10^{4}$ helium atoms generated in a supersonic expansion, represent a nanometer-sized superfluid medium of 0.4 K temperature and can be doped with one or several atoms or molecules that may form complexes in this cold environment. Using two-laser excitation schemes, we were able to identify the alkali trimers K$_3$, Rb$_3$, K$_2$Rb and KRb$_2$ in their lowest quartet states formed on helium droplets loaded with potassium and rubidium atoms and assign several excited states that underlie both Jahn-Teller and spin-orbit coupling. As helium provides a gentle and only weakly perturbing matrix, it appeared desirable to look for ways to measure fine and hyperfine structure directly in the microwave or radiofrequency regime. In preparation for experiments involving optical detection of electron spin transitions in cold molecules, we studied the electronic spin relaxation in alkali atoms and molecules that reside on the surface of a droplet. Measurements of the circular dichroism in the presence of a magnetic field showed that the populations of Zeeman sublevels in alkali atoms are not thermalized, while for dimers and trimers a temperature of 0.4 K was found, implicitly providing a first determination of the droplet s surface temperature. Optical detection of spin resonance is achieved in an optical pump-probe experiment with the electron spin transition induced in a microwave cavity in a magnetic field between the pump and probe regions. With the pump laser depleting a particular spin state by desorption of the species from the droplet beam or by optical pumping, the probe laser detects the successful spin flip induced by the microwave field. Examples will be presented showing up to 50 Rabi cycles of an electron spin transition on an alkali doped helium droplet during the flight time of 57 $\mu$s through the cavity. J.~Nagl, G.~Aubock, A.~W.~Hauser, O.~Allard, C.~Callegari, and W.~E.~Ernst, Phys.~Rev.~Lett. 100, 063001(2008).G.~Aubock, J.~Nagl, C.~Callegari, and W.~E.~Ernst, J.~Chem.~Phys. 129, 114501(2008).J.~Nagl,G.~Aubock, C.~Callegari, and W.~E.~Ernst, Phys.~Rev.~Lett. 98, 075301 (2007).G.~Aubock, J.~Nagl, C.~Callegari, and W.~E.~Ernst, J.~Phys.~Chem. A 111, 7404(2007).G.~Aubock, J.~Nagl, C.~Callegari, and W.~E.~Ernst, Phys.~Rev.~Lett. 101, 035301(2008).; Author Institution: Institute of Experimental Physics, Graz University of Technology; Petersgasse 16, A-8010 Graz, Austria

2009-01-01T00:00:00Z Ernst, Wolfgang E. Reed, B. Lam, C. S. Xing, X. Lau, K. C. Ng, C. Y. Zhang, X. Vasiliou, A. Ellison, G. B. http://hdl.handle.net/1811/38402 2009-07-30T06:19:07Z 2009-01-01T00:00:00Z

INFRARED VACUUM ULTRAVIOLET SPECTROSCOPY OF ALLYL RADICAL Reed, B.; Lam, C. S.; Xing, X.; Lau, K. C.; Ng, C. Y.; Zhang, X.; Vasiliou, A.; Ellison, G. B. An infrared (IR)-vacuum ultraviolet (VUV) double resonance experiment on the allyl (CH$_2$CHCH$_2$) radical will be described. The pulsed field ionization-photoelectron (PFI-PE) spectrum of the allyl (CH$_2$CHCH$_2$) radical has already been obtained and used to determine the accurate ionization energy of 65 584.6 +/- 2.0 cm$^{-1}$ (8.131 46 ±0.000 25 eV). Next, building on previous work which identified IR resonances at 3113.98 and 3110.59 cm$^{-1}$, we anticipate the first IR-VUV double resonance spectrum of the allyl (CH$_2$CHCH$_2$) radical. \vspace{1em} We have shown previously that high-resolution IR spectra of polyatomic neutral closed shell molecules can be obtained with high sensitivity by scanning the frequency of a single mode infrared optical parametric oscillator (IR-OPO) laser to excite the molecular species of interest and fixing the frequency of a tunable vacuum ultraviolet (VUV) laser to photoionize the IR excited species. The fact that this IR-VUV method is based on a VUV photoionization probe together with time of flight (TOF) mass spectrometry (MS) detection allows the identification of the neutral IR absorber, making the method applicable for IR spectroscopy measurements of radicals, isotopomers, and clusters, which normally exist as impure samples. Author Institution: Department of Chemistry, University of California, Davis, CA 95616; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109; University of Colorado, Boulder, CO 80309

2009-01-01T00:00:00Z Reed, B. Lam, C. S. Xing, X. Lau, K. C. Ng, C. Y. Zhang, X. Vasiliou, A. Ellison, G. B. Neill, Justin L. Muckle, Matt T. Pate, Brooks H. Lovas, F. J. Plusquellic, D. F. Remijan, A. J. http://hdl.handle.net/1811/38401 2012-12-29T07:39:28Z 2009-01-01T00:00:00Z

MICROWAVE SPECTROSCOPY OF SEVEN CONFORMERS OF 1,2-PROPANEDIOL Neill, Justin L.; Muckle, Matt T.; Pate, Brooks H.; Lovas, F. J.; Plusquellic, D. F.; Remijan, A. J. Previously, two conformations of 1,2-propanediol have been identified by microwave spectroscopy by Caminati. \textbf{86} (1981) 193-201.} Here we report the assignment of five additional conformers, two from work on a Balle-Flygare type cavity FTMW spectrometer at NIST, operating between 8 and 26 GHz, and three from a deep average scan on the chirped pulse Fourier transform microwave (CP-FTMW) spectrometer at the University of Virginia, operating between 6.5 and 18.5 GHz. All seven of the assigned conformers contain an intramolecular hydrogen bond between the two hydroxyl groups. Stark effect measurements have been performed on the cavity FTMW spectrometer to determine the dipole moments of the three lowest energy conformers. Relative abundances of the conformers have also been determined from the CP-FTMW spectrum. A subsequent interstellar search toward Sgr B2(N) yielded negative results with an upper limit to the total column density that is less than those of glycolaldehyde and ethylene glycol. W.Caminati, \textit{J. Mol. Spectrosc.; Author Institution: Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904-4319; Optical Technology Division, NIST, Gaithersburg, MD 20899-8441; National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22904-2475

2009-01-01T00:00:00Z Neill, Justin L. Muckle, Matt T. Pate, Brooks H. Lovas, F. J. Plusquellic, D. F. Remijan, A. J. Kumru, M. Bardakci, T. Sari, L. http://hdl.handle.net/1811/38400 2009-07-30T06:19:04Z 2009-01-01T00:00:00Z

DENSITY FUNCTIONAL THEORY STUDY ON MOLECULAR STRUCTURE AND VIBRATIONAL SPECTRA OF 4-AMINO-1-METHYLBENZENE Kumru, M.; Bardakci, T.; Sari, L. We have discussed the applicability limits of HF, MP2 and DFT-B3LYP methods on 4-amino-1-methylbenzene in our previous work [1]. We have found the DFT-B3LYP method very promising for vibrational spectral analyses. In this study, we extend DFT calculations with different basis sets for more appropriateness to exprimental results. The optimized molecular structures, vibrational frequencies and coresponding vibrational assigments of 4-amino-1-methylbenzene have been obtained from the DFT-B3LYP, DFT-B3PW91 and DFT-PBEPBE methods implementing the 6-311G+** and aug-ccPVQZ basis sets. Scale factors, which bring computational frequencies in closer agreement with the experimental data, have been calculated for predominant vibrational motions of the normal modes at each level considered. All observed harmonic IR and Raman bands of 4-amino-1-methylbenzene have been assigned in the frameworks of the calculations. The comparison of calculations with FT-IR and FT-Raman spectra of 4-amino-1-methylbenzene have been carried out. We are planing to extend this work to the transition metal complexes in the form of MX2L2 [M: Transition metals e.g. Mn(II), Co(II) and Ni(II) . . . ; X : Halogens e.g Cl, Br, I, L: 4-amino-1-methylbenzene] 1. A. Altun, K. Golcuk, M. Kumru, "Structure and vibrational spectra of p-methylaniline: Hartree-Fock, MP2 and density functional theory studies", JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM 637: 155-169 OCT 3 2003 Author Institution: Fatih University, Faculty of Arts and Sciences, Department of Physics, 34500 Büyükçekmece, Istanbul, TURKEY

2009-01-01T00:00:00Z Kumru, M. Bardakci, T. Sari, L. Afshari, Mahin Dehghany, M. Oliaee, J. N. Moazzen-Ahmadi, N. McKellar, A. R. W. http://hdl.handle.net/1811/38399 2012-12-29T07:38:18Z 2009-01-01T00:00:00Z

INFRARED SPECTRA OF CARBONYL SULFIDE-ACETYLENE TRIMERS: OCS-(C$_2$H$_2$)$_2$ AND TWO ISOMERS OF (OCS)$_2$-C$_2$H$_2$ Afshari, Mahin; Dehghany, M.; Oliaee, J. N.; Moazzen-Ahmadi, N.; McKellar, A. R. W. Spectra of acetylene-carbonyl sulphide trimers in the region of the OCS \nub{1} fundamental ($\sim$2062 \wn) are observed using a tunable diode laser to probe a pulsed supersonic slit jet expansion. A previous microwave study of (OCS)$_2$- C$_2$H$_2$ by Peebles and Kuczkowski \textbf{111}, 10511 (1999).} gave a nonplanar triangular twisted structure, which could be thought of as a polar OCS dimer plus a C$_2$H$_2$ monomer lying above the dimer plane. In the present work, three infrared bands are analyzed. The first band clearly belongs to this previously known (OCS)$_2$-C$_2$H$_2$ complex. The second band can be assigned as an isomer of (OCS)$_2$-C$_2$H$_2$ having a similar structure, but with a nonpolar OCS dimer plus a C$_2$H$_2$ monomer above the dimer plane. The third band is assigned to OCS-(C$_2$H$_2$)$_2$. The rotational constants and dipole moment components of all three bands are consistent with barrel shape structures having C$_1$, C$_2$ and C$_s$ symmetries, respectively. S.A. Peebles and R.L. Kuczkowski, \textit{J. Chem. Phys.; Author Institution: Department of Physics and Astronomy, University of Calgary; Calgary, AB T2N 1N4, Canada; Steacie Institute for Molecular Sciences, National Research; Council of Canada, Ottawa, ON K1A 0R6, Canada

2009-01-01T00:00:00Z Afshari, Mahin Dehghany, M. Oliaee, J. N. Moazzen-Ahmadi, N. McKellar, A. R. W. Horvath, Samantha McCoy, Anne B. Pitzer, Russell M. http://hdl.handle.net/1811/38398 2009-07-30T06:18:59Z 2009-01-01T00:00:00Z

THEORETICAL STUDIES OF TIME-RESOLVED PHOTOELECTRON SPECTRA OF IBr$^-$ Horvath, Samantha; McCoy, Anne B.; Pitzer, Russell M. In the present study, we examine the time-resolved photoelectron spectra of IBr$^-$. In the photodetachment studies performed by Sanov and co-workers and Lineberger and co-workers,}, {\bf{2005}}, {\it{122}}, 174305; Leonid Sheps, Elisa M. Miller, and W. C. Lineberger (private communication).} the anionic species, prepared in its electronic ground state ($^2\Sigma_{1/2}^+$), is excited to either its {\it{\~{A}}}$^\prime$ ($^2\Pi_{3/2}$) or {\it{\~{B}}} ($^2\Sigma_{1/2}^+$) excited state, before electron photodetachment and dissociation on the {\it{\~{C}}} ($^1\Pi_1$) or higher-lying excited states of the neutral species, respectively. In this work, we use the electronic structure program {\it{Columbus}} to calculate the six lowest electronic states of IBr$^-$ and the ten lowest $\Sigma$ states of IBr at the MR-SO-CISD/aug-cc-pVDZ level of theory/basis, using relativistic core potentials for I and Br. Experimentally determined electronic states of IBr are also used.}, {\bf{2001}}, {\it{114}}(6), 2629.} Vibrational eigenstates for these electronic states are calculated in a discrete variable representation,}, {\bf{1992}}, {\it{96}}(3), 1982.} and propagation of the thermally populated {\it{\~{X}}}-state vibrational wave functions on either the {\it{\~{A}}}$^\prime$ or {\it{\~{B}}} electronic states of the anion is performed using a Lanczos scheme. We then take time-dependent overlaps between these propagated states and the vibrational eigenstates of the neutral surface. Results for IBr$^-$ show good agreement with the experimental time-resolved spectra. Extensions to IBr$^-$(CO$_2$)$_n$ ($n < 2$) will also be discussed. R. Mabbs, K. Pichugin, and A. Sanov, {\it{J. Chem. Phys.E. Wrede, S. Laubach, S. Schulenburg, A. Brown, E. R. Wouters, A. J. Orr-Ewing, and M. N. R. Ashfold, {\it{J. Chem. Phys.D. T. Colbert and W. H. Miller, {\it{J. Chem. Phys.; Author Institution: Department of Chemistry, The Ohio State University, Columbus, OH 43210

2009-01-01T00:00:00Z Horvath, Samantha McCoy, Anne B. Pitzer, Russell M. Kuramoto, Douglas S. Zare, Richard N. Kachanov, Alexander A. http://hdl.handle.net/1811/38397 2009-07-30T06:18:59Z 2009-01-01T00:00:00Z

RAYLEIGH SCATTERING CROSS SECTION MEASUREMENTS WITH A THREE MIRROR RING CAVITY Kuramoto, Douglas S.; Zare, Richard N.; Kachanov, Alexander A. Most optical cavities in cavity ring-down spectroscopy consist of two mirrors. Using a more complicated cavity design, such as one with three mirrors, can lead to advantages such as reducing the effect of baseline variations due to reflections between the cavity mirror and the laser. A three mirror cavity in the ring configuration has been developed which uses the backward traveling wave to provide feedback to an external cavity diode laser. Measurements of Rayleigh scattering cross sections using this setup will be discussed. Author Institution: Department of Chemistry, Stanford University, Stanford, CA 94305; Skymoon Ventures, Santa Clara, CA 95054

2009-01-01T00:00:00Z Kuramoto, Douglas S. Zare, Richard N. Kachanov, Alexander A. Nicely, Amy L. Lisy, James M. http://hdl.handle.net/1811/38396 2012-12-29T07:37:50Z 2009-01-01T00:00:00Z

INFRARED SPECTRA OF M$^+$(2-AMINO-1-PHENYL ETHANOL)(H$_2$O)$_{n=0-2}$Ar (M=Na, K) Nicely, Amy L.; Lisy, James M. A balance of competing electrostatic and hydrogen bonding interactions directs the structure of hydrated gas-phase cluster ions. Because of this, a biologically relevant model of cluster structures should include the effects of surrounding water molecules and metal ions such as sodium and potassium, which are found in high concentrations in the bloodstream. The molecule 2-amino-1-phenyl ethanol (APE) serves as a model for the neurotransmitters ephedrine and adrenaline. The neutral APE molecule contains an internal hydrogen bond between the amino and hydroxyl groups. In the M$^+$(APE) complex, the cation can either interrupt the internal hydrogen bond or position itself above the phenyl group, leaving the internal hydrogen bond intact. The former is preferred based on DFT calculations (B3LYP/6-31+G*) for both K$^+$ and Na$^+$ across the entire range from 0-400K, but infrared photodissociation (IRPD) spectra indicate a preference for the latter configuration at low temperatures. The IRPD spectra of M$^+$(H$_2$O)$_{n=1-2}$ and M$^+$(H$_2$O)$_{n=0-2}$Ar (M=Na, K) will be presented along with parallel DFT and thermodynamics calculations to assist with the identification of the isomers present in each experiment. Author Institution: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801

2009-01-01T00:00:00Z Nicely, Amy L. Lisy, James M. Wang, Hailing Zhuang, Xiujuan Steimle, Timothy C. http://hdl.handle.net/1811/38395 2012-12-29T07:37:33Z 2009-01-01T00:00:00Z

THE OPTICAL STARK SPECTRA OF CoF AND CoH Wang, Hailing; Zhuang, Xiujuan; Steimle, Timothy C. Comparing the predicted and observed permanent electric dipole moments, $\mu$$_{el}$, for simple diatomic cobalt containing molecules is a means of testing computational methodologies used for modeling cobalt-catalyzed reactions. Here we report on the experimental determination of $\mu$$_{el}$ for CoH and CoF from the analysis of the Stark shifts in the (0,0) bands of the $A^{\prime}^{3}$$\Phi_{4}-X^{3}\Phi_{4}$ system of cobalt monohydride, CoH, and the $[18.8]^{3}$$\Phi_{4}-X^{3}\Phi_{4}$ system of cobalt monofluoride, CoF. In addition, the proton magnetic hyperfine interaction in CoH is analyzed. The relative values for $\mu$$_{el}$ are rationalized using a molecular orbital correlation diagram and with high-level \textit {ab initio} predictions\underline {\textbf{126}} 144307, 2007.}. Tomonari,M.; Okuda, R.; Nagashima, U.; Tanaka, K.; Hirano, T.;\textit {J.~Chem.~Phys.; Author Institution: Department of Chemistry and Biochemistry, Arizona State University, Tempe,AZ 85287

2009-01-01T00:00:00Z Wang, Hailing Zhuang, Xiujuan Steimle, Timothy C. Kumar, T. J. Dhilip Stanton, John F. Barker, John R. http://hdl.handle.net/1811/38394 2012-12-29T07:37:26Z 2009-01-01T00:00:00Z

HOONO ISOMERIZATION TO HONO$_2$ INVOLVING CONICAL INTERSECTIONS Kumar, T. J. Dhilip; Stanton, John F.; Barker, John R. The important atmospheric reactions HO$_2$ + NO and OH + NO$_2$ lead to formation and dissociation of the cis- and trans- isomers of the HOONO complex. In the present work, the global HNO$_3$ potential energy surface (PES) is being studied by using high-level ab initio electronic structure methods. This PES, 3999 (2003).} and others in the same class have been studied previously by others. In the F + NO$_2$ reaction system, UCCSD(T) calculations showed that FONO isomerizes to FNO$_2$ through a tight transition state involving a two-state avoided curve crossing, 7639 (2004).}. A similar mechanism has been invoked for HOONO, which is isoelectronic with FONO. CASSCF multi-configurational calculations on the CH$_3$O + NO$_2$ reaction located a conical intersection near where single-configurational DFT methods predict an intrinsic energy barrier; the barrier was suggested to be an artifact$ez and J. Soto, J. Phys. Chem. A {\bf 112}, 249 (2008).}. In present work, the global HNO$_3$ PES is being investigated by both the UCCSD(T) and CASSCF methods in order to study the influence of low-lying excited electronic states on the ground state PES and reaction dynamics. L. P. Olsen, M. D. Bartberger and K. N. Houk, J. Am. Chem. Soc., {\bf 125G. B. Ellison, J. M. Herbert, A. B. McCoy, J. F. Stanton and P. G. Szalay, J. Phys. Chem. A {\bf 108J. F. Arenas, F. J. Avila, J. C. Otero, D. Pel$\acute{a; Author Institution: Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48105; Institute for Theoretical Chemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712; Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48105

2009-01-01T00:00:00Z Kumar, T. J. Dhilip Stanton, John F. Barker, John R. Faraji, S. Koppel, H. http://hdl.handle.net/1811/38393 2009-07-30T06:18:49Z 2009-01-01T00:00:00Z

MULTI-STATE VIBRONIC INTERACTIONS IN FLUORINATED BENZENE RADICAL CATIONS. Faraji, S.; Koppel, H. \maketitle Conical intersections of potential energy surfaces have emerged as paradigms for signalling strong nonadiabatic coupling effects . An important class of systems where some of these effects have been analyzed in the literature, are the benzene and benzenoid cations, where the electronic structure, spectroscopy, and dynamics have received great attention in the literature. In the present work a brief overview is given over our theoretical treatments of multi-mode and multi-state vibronic interactions in the benzene radical cation and some of its fluorinated derivatives. The fluorobenzene derivatives are of systematic interest for at least two different reasons. (1) The reduction of symmetry by incomplete fluorination leads to a disappearance of the Jahn-Teller effect present in the parent cation. (2) A specific, more {\em chemical} effect of fluorination consists in the energetic increase of the lowest $ \sigma$-type electronic states of the radical cations. \par The multi-mode multi-state vibronic interactions between the five lowest electronic states of the fluorobenzene radical cations are investigated theoretically, based on {\em ab initio} electronic structure data, and employing the well-established linear vibronic coupling model, augmented by quadratic coupling terms for the totally symmetric vibrational modes. Low-energy conical intersections, and strong vibronic couplings are found to prevail within the set of $\tilde{X}$--$\tilde{A}$ and $\tilde{B}$--$\tilde{C}$--$\tilde{D}$ cationic states, while the interactions between these two sets of states are found to be weaker and depend on the particular isomer. This is attributed to the different location of the minima of the various conical intersections occurring in these systems. \par Wave-packet dynamical simulations for these coupled potential energy surfaces, utilizing the powerful multi-configuration time-dependent Hartree method ckle and G.~ A.~ Worth and H.~-D.~ Meyer, {Phys.\ Rep.} {\bf 324}, 1 (2000).} are performed. Ultrafast internal conversion processes and the analysis of the MATI and photo-electron spectra shed new light on the spectroscopy and fluorescence dynamics of these species, 074310 (2008).}. W. Domcke, D. R. Yarkony, and H. Koppel, Advanced Series in Physical Chemistry, World Scientific, Singapore (2004).M. H.~ Beck and A.~ Jackle and G.~ A.~ Worth and H.~-D.~ Meyer, {Phys.\ Rep.S.~ Faraji, H.~ Koppel, (Part I) ; S.~ Faraji, H.~ Koppel, H.-D.~ Meyer, (Part II) {J.~Chem.\ Phys. \bf 129; Author Institution: Theoretische Chemie, Physikalisch-Chemisches Institut, Universitat Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany

2009-01-01T00:00:00Z Faraji, S. Koppel, H. Wada, Ryuichi Beames, Joseph M. Orr-Ewing, Andrew J. http://hdl.handle.net/1811/38392 2012-12-29T07:44:32Z 2009-01-01T00:00:00Z

DETECTION OF IODINE MONOXIDE RADICALS IN THE MARINE BOUNDARY LAYER USING AN OPEN-PATH CAVITY RING-DOWN SPECTROMETER Wada, Ryuichi; Beames, Joseph M.; Orr-Ewing, Andrew J. An open-path cavity ring down spectroscopy (CRDS) instrument for measurement of atmospheric iodine monoxide (IO) radicals has been tested in the laboratory and subsequently deployed in Roscoff as part of the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) project in September 2006. In situ measurements are reported of local IO mixing ratios in the marine boundary layer. \underline{\textbf{58}}, 69, 2007.} The absorption cross section at the bandhead of the IO A$^2\Pi_{3/2}$ - X$^2\Pi_{3/2}$ (3,0) vibronic band was used to obtain the mixing ratios of atmospheric IO. The mixing ratios of IO were obtained on two days, peaked close to low tide, and were ~5 - 10 times higher than values calculated from column densities previously reported by long-path, differential optical absorption spectroscopy (DOAS) in coastal regions. The typical detection limit of the instrument was estimated to be 10 pptv of IO with the total accumulation time of 30 s. The observations of relatively high concentration, compared to the values previously reported by DOAS, are consistent with the concurrent observations using a LIF (Laser induced Fluorescence) instrument. \underline{\textbf{58}}, 19, 2007.} The observed IO mixing ratios fluctuated, in part, because the open-path configurations had disadvantages that included perturbation of ring-down measurements by air currents and light scattering caused by aerosols. However these problems were more than amply compensated for by elimination of unknown sampling losses. The contribution of aerosol particles to the obtained IO mixing ratios will be discussed at the meeting. R.~Wada, J.~M.~Beames and A.~J.~Orr-Ewing \textit{J.~Atoms.~Chem.L.~K.~Whalley, K.~L.~Furneaux, T.~Gravestock, H.~M.~Atkinson, C.~S.~E.~Bale, T.~Ingham, W.~J.~Bloss and D.~E.~Heard \textit{J.~Atoms.~Chem.; Author Institution: Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan; School of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom; School of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom

2009-01-01T00:00:00Z Wada, Ryuichi Beames, Joseph M. Orr-Ewing, Andrew J. Liu, Jinjun Sprecher, Daniel Raunhardt, Matthias Schafer, Martin Merkt, Frederic http://hdl.handle.net/1811/38391 2012-12-29T07:44:30Z 2009-01-01T00:00:00Z

HIGH-RESOLUTION SPECTROSCOPY OF {$n$p} RYDBERG STATES OF He$_2$: 1. RYDBERG-STATE-RESOLVED THRESHOLD IONIZATION SPECTRA OF METASTABLE He$_2$ Liu, Jinjun; Sprecher, Daniel; Raunhardt, Matthias; Schafer, Martin; Merkt, Frederic A supersonic beam of metastable He$_2^*$ a $^3\Sigma_{\rm u}^+$ molecules was generated using a pulsed discharge at the exit of a pulsed valve prior to the gas expansion into vacuum.% , \emph{J. Chem. Phys.} \textbf{128}, 164310 (2008).} Transitions to high $n$p Rydberg states were recorded using photoionization and Rydberg-state-resolved threshold ionization spectroscopy.% , \emph{Chem. Phys. Lett.} \textbf{346}, 201 (2001).} Overview scans at moderate resolution (0.3 cm$^{-1}$) were obtained with ionization fields ranging from 1.3 to 133 V/cm, lowering the ionization thresholds by 5.5 and 55 cm$^{-1}$, respectively. Using a solid-state UV laser system% , \emph{Rev. Sci. Instr.} \textbf{76}, 103103 (2005).} with a 20 MHz bandwidth, high-resolution spectra of Rydberg series with $n$ up to 150 and with resolved fine structure of the initial He$_2^*$ a $^3\Sigma_{\rm u}^+$ ($N''$) state were recorded. The assignment of the observed Rydberg states is based on multichannel quantum defect theory calculations from a recent study$^a$ of pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron and photoionization spectra of He$_2$ (see following talk). %, %\emph{J. Chem. Phys.} \textbf{128}, 164310 (2008).}. The extrapolation of the observed Rydberg series to their limits enabled the determination of the ionization energy of the a $^3\Sigma_{\rm u}^+$ state and the rotational structure of the He$_2^+$ ion with a precision of better than 20 MHz. {M. Raunhardt, M. Schafer, N. Vanhaecke, F. Merkt{R. Seiler, U. Hollenstein, G. M. Greetham, F. Merkt{R. Seiler, Th. A. Paul, M. Andrist, F. Merkt{M. Raunhardt, M. Schafer, N. Vanhaecke, F. Merkt; Author Institution: ETH Zurich, Laboratorium fur Physikalische Chemie; Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland

2009-01-01T00:00:00Z Liu, Jinjun Sprecher, Daniel Raunhardt, Matthias Schafer, Martin Merkt, Frederic Kalogerakis, K. S. Romanescu, C. Slanger, T. G. Lee, L. C. Ahmed, M. Wilson, K. R. http://hdl.handle.net/1811/38390 2012-12-29T07:44:29Z 2009-01-01T00:00:00Z

LABORATORY MEASUREMENT OF THE CO CAMERON BANDS AND VISIBLE EMISSIONS FOLLOWING VUV PHOTODISSOCIATION OF CO${_2} Kalogerakis, K. S.; Romanescu, C.; Slanger, T. G.; Lee, L. C.; Ahmed, M.; Wilson, K. R. The CO($\textit{a}^{3}$\Pi-$\textit{X}^{1}$$\Sigma^{+}$) Cameron bands are one of the most important emission features in the UV dayglow of the CO${_2}$ planets, as demonstrated in the case of Mars by the measurements performed by Mariner and Mars Express missions. One of the mechanisms to produce electronically excited CO($\textit{a}$^{3}\Pi$) is photodissociation of CO${_2}$ at wavelengths shorter than 108 nm. At wavelengths below 100 nm, new CO${_2}$ photodissociation channels open leading to formation of higher energy triplet states of CO. These states cascade into the lower triplet state by emission in the visible spectral region before radiating in the Cameron system. This two step relaxation pathway was demonstrated by Lee and Judge, 104 (1973)} for the 90-93 nm photodissociation of CO${_2}$. We have further investigated this process using the 85-110 nm tunable synchrotron radiation at the Advanced Light Source facility at Lawrence Berkeley Laboratory. The experimental results confirmed that once a triplet state excitation threshold is exceeded, a fraction of the Cameron band emission is accompanied by visible emission. These results indicate that the emission corresponding to the CO($\textit{a}^{\prime}$-\textit{a}, \textit{d}-\textit{a}, \textit{e}-\textit{a}) triplet bands must be part of the visible Mars / Venus dayglow. The same is true for CO${_2}$ photoexcitation in cometary atmospheres. \vspace{1em} This work was supported by the NASA Outer Planets Research Program under grant NNX06AB82G. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. D.~L.~Judge~and~L.~C.~Lee, ~J.~Chem.~Phys., \textbf{58; Author Institution: SRI International, Mol. Phys. Lab., Menlo Park, CA 94025; San Diego State Univ., Dept. Elect. \& Comp. Eng., San Diego, CA 92182

2009-01-01T00:00:00Z Kalogerakis, K. S. Romanescu, C. Slanger, T. G. Lee, L. C. Ahmed, M. Wilson, K. R. Smith, M. A. H. Devi, V. Malathy Benner, D. Chris Blake, T. A. Sams, R. L. http://hdl.handle.net/1811/38389 2009-07-30T06:18:36Z 2009-01-01T00:00:00Z

MEASUREMENTS OF THE CO$_2$ 15 $\mu$m BAND SYSTEM BROADENED BY AIR, N$_2$ AND CO$_2$ AT TERRESTRIAL ATMOSPHERIC TEMPERATURES Smith, M. A. H.; Devi, V. Malathy; Benner, D. Chris; Blake, T. A.; Sams, R. L. In earth remote sensing, retrievals of atmospheric temperature profiles are often based on observed radiances in infrared spectral regions where emission from atmospheric CO$_2$ predominates. To achieve improved retrieval accuracy, systematic errors in the forward model must be reduced, especially those associated with errors in the spectroscopic line calculation. We have recorded more than 110 new high-resolution infrared spectra of the 15-$\mu$m band system of CO$_2$ to accurately determine line intensities, self-, air- and N$_2$-broadened widths and pressure-induced line shifts, along with their temperature dependences. The spectra were recorded with the Bruker IFS 120 HR Fourier transform spectrometer at Pacific Northwest National Laboratory (PNNL) and temperature-controlled sample cells. Sample temperatures were between 206K and 298K. Maximum total pressures were 15 Torr for self-broadening and 613 Torr for air- and N$_2$-broadening. Analysis is done using a multispectrum fitting technique, 705-721 (1995)} to retrieve the spectroscopic parameters. Line mixing and other non-Lorentz, non-Voigt line shapes are also assessed. The resulting line parameters are compared with the HITRAN database, 139-204 (2005); L.S.~Rothman et al., J. Quant. Spectrosc. Radiat. Transfer, in press (2009)} and with other measurements. D.~Chris Benner, C.P.~Rinsland, V.~Malathy Devi, M.A.H.~Smith, and D.~Atkins, J. Quant. Spectrosc. Radiat. Transfer {\bf 53L.S.~Rothman et al., J. Quant. Spectrosc. Radiat. Transfer {\bf 96; Author Institution: Science Directorate, NASA Langley Research Center, Hampton, VA 23681; Department of Physics, The College of William and Mary, Williamsburg, VA 23187; William R. Wiley Environmental Molecular Sciences Laboratory; Pacific Northwest National Laboratory, Richland, WA 99352

2009-01-01T00:00:00Z Smith, M. A. H. Devi, V. Malathy Benner, D. Chris Blake, T. A. Sams, R. L. Dmitriev, Yurij A. Benetis, Nikolas-Ploutarch http://hdl.handle.net/1811/38388 2012-12-29T07:44:26Z 2009-01-01T00:00:00Z

ROTATION AND MATRIX EFFECTS ON THE EPR SPECTRA OF METHYL RADICALS TRAPPED IN GAS SOLIDS Dmitriev, Yurij A.; Benetis, Nikolas-Ploutarch A study is presented on EPR spectra of methyl radicals, CH$_3$, matrix-isolated in gas solids at liquid helium temperatures. It was shown very recently \underline {\textbf{21}}(10), 103201 March 2009.} that the peculiar features of the trapped methyl rotor are attributed to the quantum effects of inertial rotary motion and its coupling to the nuclear-spin of the radical. Here, we report an investigation of the spectrum saturation behaviour and present a qualitative consideration of the spectrum anisotropy found earlier. However the broadening is by far smaller than in the expected powder of a fully anisotropic radical with rhombic $hf$-interaction and $g$-tensor anisotropy in the solid state. It is present as an asymmetric lineshape of the basic lowest rotational level EPR quartet with cross-relaxation due to the combination of the above mentioned hf interaction with the anisotropic Zeeman one. Splitting of the relatively sharp lines is also observed due to these interactions as well as due to the superimposition of the spectra of the CH$_3$ radical in other possible sites and/ or defects of the solid Kr-matrix, as well as from the first nontrivial rotational level. This is actually the only indication of the matrix interaction with the methyl radical which seems otherwise to perform almost free $3D$ rotation in the voids of the more or less ``inert'' matrix. Of course the basic reason for this behaviour is partially due to the insufficient transfer of thermal energy from the ``lattice'' to the radical motional degrees of freedom at these low temperatures of the experiments, between 1.5 and 5 K. We give prove that the anisotropy is governed, for the most part, by the repulsion interaction between the CH$_3$ radical and a matrix particle, while a matrix shift of the methyl hyperfine coupling constant is linked to both the repulsion and the attraction interactions. Nikolas~P.~Benetis and Yurij~Dmitriev \textit {J.~Phys.:~Condens.~Matter; Author Institution: Ioffe Physical-Technical Institute, 26 Politekhnicheskaya str.,194021 St. Petersburg, Russia; Department of Pollution Control, Technological Educational Institution, TEI, West Macedonia, Kozani 501 00, Greece

2009-01-01T00:00:00Z Dmitriev, Yurij A. Benetis, Nikolas-Ploutarch De Lucia, Frank C. http://hdl.handle.net/1811/38387 2012-12-29T07:44:10Z 2009-01-01T00:00:00Z

ASTRONOMICAL AND ATMOSPHERIC SPECTROSCOPY IN THE SMM/THz: EXPERIMENTS, ANALYSIS, AND CATALOGS. De Lucia, Frank C. For many years the needs of the astronomical and atmospheric science communities have directly or indirectly motivated much of the work at this symposium. Interestingly, the power and sophistication of the field instruments have grown at such a rate that the needs for laboratory data seem to be diverging rather than converging. The central role played by catalogs will be discussed, as well as their impact on the spectroscopic community. Author Institution: Department of Physics, 191 W. Woodruff Ave., Ohio State University, Columbus, OH 43210 USA

2009-01-01T00:00:00Z De Lucia, Frank C. Paulson, Leif O. Anderson, David T. http://hdl.handle.net/1811/38386 2012-12-29T07:18:10Z 2009-01-01T00:00:00Z

INVESTIGATION OF THE AMIDE I BAND OF N-METHYLACETAMIDE IN SOLID PARAHYDROGEN USING FTIR SPECTROSCOPY Paulson, Leif O.; Anderson, David T. We report the FTIR spectra of the Amide I and Amide A vibrational modes of N-methylacetamide (NMA, CH$_3$CONHCH$_3$) isolated in a solid parahydrogen (pH$_2$) matrix. NMA is one of the simplest molecules that contains the peptide bond and has therefore been the subject of numerous studies, especially those concerning peptide structure and dynamics. Solid pH$_2$ is a unique quantum solid matrix host that, among other features, allows for high-resolution IR studies of trapped dopant species. In our preliminary report, talk R008 (2006)} we showed that the Amide I lineshape was surprisingly broad and shifts were observed with small changes in temperature. That talk did not resolve the origin of these shifts with temperature that require many minutes to fully equilibrate. Further investigations have revealed that the frequency and breadth of the transition depends partially on the orthohydrogen concentration in the matrix. The Amide I lineshape displays both reversible and irreversible components that are dependent upon the temperature of the host matrix. This talk will discuss possible explanations for the breadth and temperature dependence of the Amide I feature of NMA isolated in solid pH$_2$. L.~O.~Paulson and D.~T.~Anderson, \textit{61st Ohio State University International Symposium on Molecular Spectroscopy,; Author Institution: Department of Chemistry, University of Wyoming, Laramie, WY 82071-3838

2009-01-01T00:00:00Z Paulson, Leif O. Anderson, David T. Case, Amanda S. Yoon, Y. Heidi Crim, F. Fleming http://hdl.handle.net/1811/38385 2012-12-29T07:43:03Z 2009-01-01T00:00:00Z

DYNAMICS OF VIBRATIONALLY EXCITED PHENOL-CO Case, Amanda S.; Yoon, Y. Heidi; Crim, F. Fleming The dynamics of vibrationally excited complexes can be very intriguing, particularly the inefficient energy transfer and nonstatistical predissociation caused by the mismatch in frequencies of inter- and intra-molecular vibrational modes. We are looking at such dynamics in the one-to-one complex of phenol with carbon monoxide. These complexes are weakly bound by about 660 cm$^{-1}$ in a planar minimum consisting of a nearly linear hydrogen bond between the phenolic hydrogen and the carbon end of the CO moiety. Both dissociation products (phenol and CO) can be conveniently probed with REMPI. We are taking advantage of this to study the dynamics of vibrationally excited phenol-CO. Looking beyond energy transfer and vibrational predissociation, it would be interesting to study both the one-photon and vibrationally mediated photodissociation dynamics of hydrogen production in this complex. Such studies could provide information on the effect the CO has on the dissociation of phenol, emphasizing its influence at the conical intersections. Author Institution: The University of Wisconsin - Madison Department of Chemistry, 1101 University Avenue, Madison, WI 53705

2009-01-01T00:00:00Z Case, Amanda S. Yoon, Y. Heidi Crim, F. Fleming Le Roy, Robert J. Meshkov, Vladimir V. Stolyarov, Andrej V. http://hdl.handle.net/1811/38384 2009-07-30T17:41:03Z 2009-01-01T00:00:00Z

ADAPTIVE ANALYTIC MAPPING PROCEDURES FOR SIMPLE AND ACCURATE CALCULATION OF SCATTERING LENGTHS AND PHOTOASSOCIATION ABSORPTION INTENSITIES Le Roy, Robert J.; Meshkov, Vladimir V.; Stolyarov, Andrej V. We have shown that one and two-parameter analytical mapping functions such as $~r(y;\bar{r}, \alpha)=\bar{r}\left[1\,+\,\frac{1}{\alpha}~\tan(\pi y/2)\right]~$ and $~r(y;\bar{r})=\bar{r} \left[ \frac{1+ y}{1-y} \right]~$ transform the conventional radial Schr{\" o}dinger equation into equivalent alternate forms \vspace{-2mm} $$ \frac{d^2\phi(y)}{dy^2}~=~ \left[\frac{\pi^2}{4}+\left(\frac{2\mu} {\hbar^2} \right) g^2(y) \,[E - U(r(y))]\right]\phi(y) \hspace{7mm} {\rm and} \hspace{7mm} \frac{d^2\phi(y)}{dy^2}~=~\left(\frac{2\mu}{\hbar^2}\right) g^2(y)\left[E - U(r(y)) \right]\phi(y) \vspace{-2mm} $$ % respectively, in which $\,g(y)=dr(y)/dy\,$. \textbf{78}, 052510 (2008).}~ Such transformed equations are defined on the finite domain $\,y\in [-1,1]$, and they may be solved routinely using standard numerical methods at all energies up to and including the potential asymptote. At the energy of the potential asymptote, the $s$-wave scattering length $a_s$ can be expressed in terms of the logarithmic derivative of the wave function $\phi(y)$ at the right-hand boundary point: \vspace{-2mm} $$ a_s~=~\bar{r}\left[\frac{2} {\pi\alpha}~\frac{1} {\phi(y)}~\frac{d\phi(y)} {dy}+1\right]_{y=1} \hspace{7mm} {\rm and} \hspace{7mm} a_s~=~\bar{r}\left[\,2~\frac{1}{\phi(y)}~\frac{d\phi(y)}{dy}~-1\right]_{y=1} $$ % The required logarithmic derivative of $\phi(y)$ can be obtained efficiently by direct outward integration of the differential equation all the way to the end point $\,y\!=\!1$, which corresponds to the limit $\,r\to \infty$. This zero-energy wavefunction may also be combined with wavefunctions for ordinary bound states generated in the same manner$^a$ to calculate photoassociation absorption matrix elements using any appropriately modified Franck-Condon computer program. \smallskip VVM is grateful to INTAS grant 06-1000014-5964 for support. \,V.V.\ Meshkov, A.V.\ Stolyarov, and R.J.\ Le Roy, \textit{Phys.~Rev.~A; Author Institution: Guelph-Waterloo Centre for Graduate Work in Chemistry and; Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada; Department of Chemistry, Moscow State University, GSP-2 Leninskie Gory; 1/3, Moscow 119991, Russia

2009-01-01T00:00:00Z Le Roy, Robert J. Meshkov, Vladimir V. Stolyarov, Andrej V. Didriche, K. Lauzin, C. De Ghellinck, X. Macko, P. Rizopoulos, A. Poucke, P. Van Herman, M. Kassi, S. http://hdl.handle.net/1811/38383 2012-12-29T07:44:46Z 2009-01-01T00:00:00Z

THE FANTASIO SET-UP (I): DESCRIPTION AND EXTENSION TOWARDS FEMTO-FANTASIO Didriche, K.; Lauzin, C.; De Ghellinck, X.; Macko, P.; Rizopoulos, A.; Poucke, P. Van; Herman, M.; Kassi, S. We have built the FANTASIO set-up (for "Fourier trANsform, Tunable diode and quadrupole mAss spectrometers interfaced to a Supersonic expansIOn") to investigate jet-cooled molecules and dimers, 843 (2007). }. The set-up will be described. New developments are on the way, to be illustrated by preliminary results. These include the doubling of the vacuum pumping system efficiency. They will also allow for a Femto OPO system to be used as a broadband, cavity enhanced absorption source to be interfaced to the supersonic expansion and to the high resolution FTIR instrument of FANTASIO. M. Herman, K. Didriche, D. Hurtmans, B. Kizil, P. Macko, A. Rizopoulos and P. Van Poucke, Mol. Phys., \underline{105; Author Institution: Service de Chimie quantique et Photophysique CP160/09, Faculte des Sciences, Universite Libre de; Bruxelles (U.L.B.), Av. Roosevelt, 50, B-1050, Bruxelles, Belgium; Laboratoire de; Spectrometrie Physique, Laboratoire de Spectrométrie Physique, Universite Joseph Fourier de; Grenoble, B.P. 87, 38402 Saint-Martin-d'Heres Cedex, France

2009-01-01T00:00:00Z Didriche, K. Lauzin, C. De Ghellinck, X. Macko, P. Rizopoulos, A. Poucke, P. Van Herman, M. Kassi, S. Diez-y-Riega, Maria H. Manzanares, Carlos E. http://hdl.handle.net/1811/38382 2012-12-29T07:44:44Z 2009-01-01T00:00:00Z

VIBRATIONAL OVERTONE SPECTRA OF $C_2H_6$ AND $C_2H_4$ IN CRYOGENIC LIQUIDS Diez-y-Riega, Maria H.; Manzanares, Carlos E. Vibrational overtone spectra of $C_2H_6$ and $C_2H_4$ in cryogenic solutions were recorded between 5000 and 14000 cm$^{-1}$. Spectral regions for the first four overtones were measured using a Fourier transform spectrophotometer. The fifth overtone $(\Delta\nu=6)$ spectra between 15,000 and 16,000 cm$^{-1}$ were recorded with a double beam (pump-probe) thermal lens technique using concentrations as low as 10$^{-3}$ mole fraction. The peak frequency shift $(\Delta\omega)$ from gas phase to solution is explained by the change in harmonic frequency and anharmonicity in solution with respect to the gas phase values. The bandwidth $(\Delta\omega_{1/2})$ of the $(\Delta\nu= 6)$ C-H absorption bands in solution can be explained in terms of collisions with the solvent molecules. Author Institution: Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, 76798

2009-01-01T00:00:00Z Diez-y-Riega, Maria H. Manzanares, Carlos E. Chen, L. Woon, D. E. Dunning, T. H. Jr. http://hdl.handle.net/1811/38381 2012-12-29T07:44:43Z 2009-01-01T00:00:00Z

UNDERSTANDING THE MOLECULAR PROPERTIES OF ClF$_n$ ({$n=$1-7}) SPECIES: AN APPLICATION OF THE RECOUPLED PAIR BONDING MODEL FOR HYPERVALENT BONDS Chen, L.; Woon, D. E.; Dunning, T. H. Jr. Recently, new insight into the nature of hypervalent behavior led us to develop a model called recoupled pair bonding. In this model, two hypervalent bonds can be formed by decoupling a valence $p^2$ or $s^2$ electron pair. However, energy must be expended to decouple an electron pair, and the first bond is weakened as a consequence. The recoupled pair bonding model has been proven successful in our initial study of the SF$_n$ ({$n=$1-7}) species. To further examine the applicability of this new model, this study explored the molecular properties of the ClF$_n$ ({$n=$1-7}) series. Optimized ground state structures, bond energies, and spectral properties of these molecules were obtained by employing high level ab initio calculations [MRCI, CCSD(T)] with correlation consistent basis sets. Because of recoupled pair bonding, there are unanticipated low-lying excited states such as ClF (${^3}{\Pi}$) and ClF$_2$ (${^2}{\Pi}$,${^4}{\Sigma}$). We also systematically explored the bond formation processes, adding F atoms one at a time to the optimized ClF$_n$ ({1 $\leq n \leq$ 6 }) molecules. We find the bond energies for F addition to form ClF$_2$, ClF$_4$, and ClF$_6$ are much lower than those leading to ClF, ClF$_3$ and ClF$_5$. This oscillating trend is analogous to what is seen in the SF$_n$ species, though the bond energies of the SF$_n$ species are considerably greater than the ones for ClF$_n$. The lower bond energies of the even $n$ species in the ClF$_n$ series reflects the cost of decoupling paired electrons of the central atom, and the difference between ClF$_n$ and SF$_n$ reflects the fact that more energy is needed to decouple each of the $3p^2$ pairs of electrons of Cl than the single $3p^2$ pair of S. This behavior and other trends observed in ClF$_n$ species demonstrate the improved predictive ability of the recoupled pair bonding model over other models for describing hypervalent bonding. Author Institution: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801

2009-01-01T00:00:00Z Chen, L. Woon, D. E. Dunning, T. H. Jr. Twagirayezu, Sylvestre Clasp, Trocia N. Perry, David S. Neill, Justin L. Muckle, Matt T. Pate, Brooks H. http://hdl.handle.net/1811/38380 2012-12-29T07:44:42Z 2009-01-01T00:00:00Z

CONFIRMATION OF VIBRATION COUPLING IN THE SYMMETRIC CH STRETCH AS REVEALED BY COHERENCE-DETECTED FTMW-IR SPECTROSCOPY OF CH$_3$OD. Twagirayezu, Sylvestre; Clasp, Trocia N.; Perry, David S.; Neill, Justin L.; Muckle, Matt T.; Pate, Brooks H. \maketitle Rotational state-selection with E-species transitions ($3_0\leftarrow 3_{-1}$,$2_0\leftarrow 3_1$,$1_0\leftarrow 1_1$) is employed to record the infrared spectra in the range 2750-2900 cm$^{-1}$. The observed spectra of CH$_3$OD contain only one vibrational band origin whereas 12 interacting vibrational bands of CH$_3$OH are observed in the same interval. There are no interacting vibrational bands in the CH$_3$OD spectra because the first tier states are shifted out of resonance. This observation confirms that the dominant coupling pathway in the $\nu _3$ CH stretch of CH$_3$OH is the third order coupling of the CH stretch to a combination of the COH bend and an HCH bend, which subsequently couples to high order combination bands involving torsional excitation. Author Institution: Department of Chemistry, The University of Akron, Akron OH 44325; Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904

2009-01-01T00:00:00Z Twagirayezu, Sylvestre Clasp, Trocia N. Perry, David S. Neill, Justin L. Muckle, Matt T. Pate, Brooks H. Filsinger, Frank Kupper, Jochen Meijer, Gerard Hansen, Jonas L. Holmegaard, Lotte Nielsen, Jens H. Nevo, Iftach Maurer, Jochen Stapelfeldt, Henrik http://hdl.handle.net/1811/38379 2009-07-30T06:17:43Z 2009-01-01T00:00:00Z

SPATIALLY SEPARATING STRUCTURAL ISOMERS OF NEUTRAL MOLECULES Filsinger, Frank; Kupper, Jochen; Meijer, Gerard; Hansen, Jonas L.; Holmegaard, Lotte; Nielsen, Jens H.; Nevo, Iftach; Maurer, Jochen; Stapelfeldt, Henrik Large (bio)molecules exhibit multiple conformers (structural isomers), even under the cold conditions present in a supersonic jet. For various applications, i.\,e., scattering experiments or time resolved studies, it would be highly desirable to prepare molecular packets of individual conformers. It is well known that polar molecules can be manipulated using strong electric fields. Recently, we have demonstrated that electrostatic deflection of a molecular beam can be used for quantum-state selection of large molecules.~, \textbf{102}, (2009),023001 } Here, we demonstrate how this quantum state selectivity can be exploited to spatially separate the individual conformers of large molecules based on their distinct mass-to-dipole moment (m/$\mu$) ratios. In a proof-of-principle experiment, we have spatially isolated both, cis and trans, conformers of 3-aminophenol. We will compare this approach to conformer selection using alternating gradient (dynamic) focusing in an m/$\mu$-selector.~ \textbf{100}, (2008),133003} L. Holmegaard et al., \textit{Phys.~Rev.~Lett.F. Filsinger et al., \textit{Phys.~Rev.~Lett.; Author Institution: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195; Berlin, Germany; Department of Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark

2009-01-01T00:00:00Z Filsinger, Frank Kupper, Jochen Meijer, Gerard Hansen, Jonas L. Holmegaard, Lotte Nielsen, Jens H. Nevo, Iftach Maurer, Jochen Stapelfeldt, Henrik Zack, L. N. Pulliam, R. L. Ziurys, L. M. http://hdl.handle.net/1811/38378 2012-12-29T07:44:41Z 2009-01-01T00:00:00Z

THE PURE ROTATIONAL SPECTRA OF ZnO IN THE EXCITED a$^{3}\Pi_i$ STATE Zack, L. N.; Pulliam, R. L.; Ziurys, L. M. The pure rotational spectra of ZnO in the excited a$^{3}\Pi_i$ electronic state have been measured using direct absorption sub-millimeter techniques. This molecule was synthesized by reacting zinc vapor with N$_2$O in the presence of a DC discharge. Nine rotational transitions were recorded for the $^{64}$ZnO, $^{66}$ZnO, and $^{68}$ZnO isotopomers in the v=0 state and data for the main isotopomer was measured in the v=1 state. All three spin components were observed for this state, each exhibiting lambda-doubling. The data were fit with a Hund case(a) Hamiltonian and rotational, spin-orbit, spin-spin, and lambda-doubling constants established. A bond length of 1.8436 \AA{} was determined for this excited state, which is about 0.14 \AA{} larger than that of the ground state. Author Institution: Department of Chemistry, Department of Astronomy, Steward Observatory, University of Arizona, Tucson, AZ 85721

2009-01-01T00:00:00Z Zack, L. N. Pulliam, R. L. Ziurys, L. M. Shen, Lei Kim, Myung Hwa Zhang, Bailin Suits, Arthur G. http://hdl.handle.net/1811/38377 2012-12-29T07:44:37Z 2009-01-01T00:00:00Z

CONFORMER SELECTIVE AND VIBRATIONALLY MEDIATED PHOTODISSOCIATION STUDY OF PROPANAL CATION Shen, Lei; Kim, Myung Hwa; Zhang, Bailin; Suits, Arthur G. We report the conformationally and vibrationally selected imaging study of propanal obtained by resonance-enhanced multiphoton ionization (REMPI). The photoelectron spectra, employing the (2+1) ionization via the (n, 3s) Rydberg transitions in the range from 365 to 371 nm, confirm that there are two stable conformer origins in the lowest ionic state, the cis conformer with a co-planar CCCO geometry and a gauche conformer with a ~119° CCCO dihedral angle. We also study the photodissociation dynamics of propanal cation initially prepared in some certain vibrational modes or conformation. The product kinetic energy distributions for the H elimination channels are bimodal, and the two peaks are readily assigned to propanal cation + H and hydroxyallyl cation + H. The ratio of the fast product with respect to the whole product is varied according to different vibrational mode preparation. However, cis form appears the lowest and gauche form yield the highest ratio. Full multiple spawning dynamical calculations show that distinct ultrafast dynamics in the excited state leads to internal conversion to the ground state in isolated regions of the potential surface for the two conformers, and from these distinct regions, conformer interconversion does not effectively compete with dissociation. Author Institution: Department of Chemistry, Wayne State University, Detroit, MI, 48202

2009-01-01T00:00:00Z Shen, Lei Kim, Myung Hwa Zhang, Bailin Suits, Arthur G. Guss, Joseph S. Metsala, Markus Halonen, Lauri http://hdl.handle.net/1811/38376 2012-12-29T07:18:08Z 2009-01-01T00:00:00Z

MEDICAL DIAGNOSTIC BREATH ANALYSIS BY CAVITY RING DOWN SPECTROSCOPY Guss, Joseph S.; Metsala, Markus; Halonen, Lauri Certain medical conditions give rise to the presence of chemicals in the bloodstream. These chemicals --- known as biomarkers --- may also be present in low concentrations in human breath. Cavity ring down spectroscopy possesses the requisite selectivity and sensitivity to detect such biomarkers in the congested spectrum of a breath sample. The ulcer-causing bacterium, \textit{Helicobacter pylori}, is a prolific producer of the enzyme urease, which catalyses the breakdown of urea ((NH$_2$)$_2$CO) in the stomach as follows: \vspace{0.5cm} \hspace{3cm}(NH$_2$)$_2$CO + H$_2$O $\stackrel{\rm(urease)}{\longrightarrow}$ CO$_2$ + 2NH$_3$ \vspace{0.5cm} Currently, breath tests seeking altered carbon-isotope ratios in exhaled CO$_2$ after the ingestion of $^{13}$C- or $^{14}$C-labeled urea are used to diagnose \textit{H. pylori} infection. \underline{\textbf{1}}(8543), 1174-7 March 1987.} We present recent results from an ongoing collaboration with Tampere Area University Hospital. The study involves 100 patients (both infected and uninfected) and concerns the possible correlation between the bacterial infection and breath ammonia. D.~Y.~Graham, P.~D.~Klein, D.~J.~Evans,~Jr, D.~G.~Evans, L.~C.~Alpert, A.~R.~Opekun, T.~W.~Boutton, \textit{Lancet; Author Institution: Laboratory of Physical Chemistry, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland

2009-01-01T00:00:00Z Guss, Joseph S. Metsala, Markus Halonen, Lauri Halfen, D. T. Clouthier, D. J. Ziurys, L. M. http://hdl.handle.net/1811/38375 2009-07-30T06:17:38Z 2009-01-01T00:00:00Z

THE PURE ROTATIONAL SPECTRUM OF HPS (\ {X}$^1$A$^{\prime}$): THE THIRD ROW ANALOG OF HNO Halfen, D. T.; Clouthier, D. J.; Ziurys, L. M. The pure rotational spectrum of HPS (\~{X}$^{1}$A$^{\prime}$) has been measured using millimeter-wave direct absorption techniques in the range 229-415 GHz. This work is the first laboratory detection of this species in the gas phase. This molecule was created by the reaction of gas-phase phosphorus and H$_2$S in the presence of argon carrier gas and an AC glow discharge. The pattern of the rotational spectrum clearly indicated the presence of an asymmetric top. HPS, like HNO, has a bent structure. Data have been recorded for multiple K$_a$ components from K$_a$ = 0 to 6. The data have been fit with an asymmetric top Hamiltonian, and the spectroscopic parameters have been determined. The structure established from the rotational constants is in excellent agreement with ab initio calculations. Comparison with HNO suggests similar bonding in HPS despite the third row elemental substitutions. Author Institution: Department of Chemistry, Department of Astronomy, and Steward Observatory, University of Arizona, Tucson, AZ 85721; Department of Chemistry, University of Kentucky, Lexington, KY 40506; Department of Chemistry, Department of Astronomy, and Steward Observatory, University of Arizona, Tucson, AZ 85721

2009-01-01T00:00:00Z Halfen, D. T. Clouthier, D. J. Ziurys, L. M. Gottlieb, Carl A. Thaddeus, Patrick http://hdl.handle.net/1811/38374 2012-12-29T07:44:52Z 2009-01-01T00:00:00Z

NEW LABORATORY MEASUREMENTS OF RHOMBOIDAL SiC$_3$ Gottlieb, Carl A.; Thaddeus, Patrick Rhomboidal SiC$_3$, the highly polar planar ring with C$_{2v}$ symmetry and a transannular C---C bond, was detected in our laboratory about 10~years ago, {\bf 111}, 3911 (1999).} and soon afterwards was identified with a radio telescope in the expanding envelope of IRC+10216. {\bf 516}, L103 (1999).} Recently a sensitive spectral line survey of IRC+10216 was made with the Submillimeter Array (SMA) in the $300 - 355$~GHz range with a $3^{\prime\prime} \times 2^{\prime\prime}$ synthesized beam. Many new lines were detected in this survey. Most are from high rotational transitions of molecules that are known in IRC+10216, but some of the lines are quite narrow and more than 10 of these are unassigned.nken, R.~W.~Wilson, P.~Thaddeus, K.~M.~Menten, M.~Reid, M.~C.~McCarthy, Dinh-V~Trung, C.~A.~Gottlieb, and A.~Hedden, {\sl Astrophys. Journ.}, in press (2009).} In support of the SMA observations we have extended the earlier laboratory measurements by Apponi {\it et al.} from 286~GHz and $K_a \le 6$, to 450~GHz and $K_a \le 20$ from rotational levels as high as 825~K above ground. As a result uncertainties in the predicted spectrum for lines with high $K_a$ have been reduced by as much as two orders of magnitude, which should aid the assignment of SiC$_3$ in the SMA survey and in future observations with ALMA. % ########################################################################################### A.~J.~Apponi, M.~C.~McCarthy, C.~A.~Gottlieb, and P.~Thaddeus, {\sl Journ. Chem. Phys.A.~J.~Apponi, M.~C.~McCarthy, C.~A.~Gottlieb, and P.~Thaddeus, {\sl Astrophys. Journ. Lett.N.~A.~Patel, K.~H.~Young, S.~Brunken, R.~W.~Wilson, P.~Thaddeus, K.~M.~Menten, M.~Reid, M.~C.~McCarthy, Dinh-V~Trung, C.~A.~Gottlieb, and A.~Hedden, {\sl Astrophys. Journ.; Author Institution: Harvard-Smithsonian Center for Astrophysics 60 Garden St. Cambridge, MA 02138; and School of Engineering \& Applied Sciences, Harvard University, 29 Oxford St.,Cambridge, MA 02138

2009-01-01T00:00:00Z Gottlieb, Carl A. Thaddeus, Patrick Zack, L. N. Ziurys, L. M. http://hdl.handle.net/1811/38373 2012-12-29T07:18:07Z 2009-01-01T00:00:00Z

SUBMILLIMETER SPECTROSCOPY OF ZnOH (X$^{2}$A$^{\prime }$): STRUCTURE AND BONDING IN 3d HYDROXIDE SPECIES Zack, L. N.; Ziurys, L. M. The ZnOH radical (X$^{2}$A$^{\prime }$) has been observed in the laboratory using mm/sub-mm direct-absorption techniques. This is the first gas-phase laboratory spectroscopic study of this radical. ZnOH was produced by reacting zinc vapor with H$_2$O or H$_2$O$_2$ under DC discharge conditions. Multiple rotational transitions have been recorded in the 400-540 GHz range that clearly exhibit K-ladder structure, indicative of a bent molecule. the pattern has been observed in three zinc isotopologues: $^{64}$ZnOH, $^{66}$ZnOH, and $^{68}$ZnOH. Each line consists of spin-rotation doublets with a splitting of $\sim$180-190 MHz, characteristic of zinc. The data are currently being analyzed and rotational and spin-rotation constants will be presented. The bent geometry suggests predominantly covalent bonding between zinc and oxygen. Author Institution: Department of Chemistry, Department of Astronomy, and Steward Observatory, University of Arizona, Tucson, AZ, 85721

2009-01-01T00:00:00Z Zack, L. N. Ziurys, L. M. Martinez, Todd J. http://hdl.handle.net/1811/38372 2009-07-30T06:17:32Z 2009-01-01T00:00:00Z

FIRST PRINCIPLES DYNAMICS AROUND CONICAL INTERSECTIONS: THE ROLE OF THE ENVIRONMENT AND INTERSECTION TOPOGRAPHY Martinez, Todd J. We discuss some recent examples, drawn from small molecules and chromophores in solvated/protein environments, of excited state dynamics using the ab initio multiple spawning method. We explore the role of the environment in altering the energetics of conical intersections and/or their topography, e.g. sloped vs peaked. A first attempt at a rate theory incorporating these aspects will be presented and compared to dynamics results. A key question which we comment on is the number of degrees of freedom which should be required in such a rate model. Is a single reaction coordinate sufficient, or are conical intersection dynamics inextricably multi-dimensional? Author Institution: Department of Chemistry, Stanford University, Stanford, CA

2009-01-01T00:00:00Z Martinez, Todd J. Dewberry, Chris T. Grubbs, Garry S., II Etchison, Kerry C. Cooke, Stephen A. http://hdl.handle.net/1811/38371 2012-12-29T07:56:06Z 2009-01-01T00:00:00Z

MEASUREMENT OF THE VIBRATIONAL POPULATION DISTRIBUTION OF BARIUM SULFIDE SEEDED IN AN ARGON SUPERSONIC EXPANSION FOLLOWING PRODUCTION THROUGH THE REACTION OF LASER ABLATED BARIUM WITH CARBONYL SULFIDE Dewberry, Chris T.; Grubbs, Garry S., II; Etchison, Kerry C.; Cooke, Stephen A. A chirped pulsed Fourier transform microwave spectrometer has been used to examine the reaction products of laser ablated barium with carbony sulfide. We find the $J$ = 2 - 1, $\nu$ = 0, transition for $^{138}$Ba$^{32}$S, at 12370.1938(20) MHz, is 8.94 times as intense as the same transition for the $^{136}$Ba$^{32}$S isotopologue, at 12404.4384(20) MHz. This is in reasonable agreement to the ratio of the natural abundances of $^{138}$Ba : $^{136}$Ba = 9.12 : 1. Given this agreement we are able to use the $^{138}$Ba$^{32}$S $J$ = 2 - 1 spectra to qualitatively monitor vibrational populations of BaS in the supersonic expansion following the ablation event. We are able to see the $J$ = 2 - 1 rotational transition for the parent isotopologue in up to the $\nu$ = 6 vibrational level. The ablation conditions have been altered, i.e. Nd:YAG laser power, laser pulse duration, backing gas pressure, OCS (H$_2$S) concentration, and carrier gas (Ar, Ne, 30:70 He:Ne and pure He), and the effects on the BaS spectrum monitored. We can also monitor OCS depletion due to the laser event by running the experiment with the laser on then off. Along side these experiments we have also recorded the nuclear quadrupole coupling constants, $eQq$($^{137}$Ba) and $eQq$($^{135}$Ba) in BaS and performed a multi-isotopomer fit to the experimental data. Results will be presented. Author Institution: The Department of Chemistry, University of North Texas, P.O. Box 305070, Denton, TX, 76203-5070

2009-01-01T00:00:00Z Dewberry, Chris T. Grubbs, Garry S., II Etchison, Kerry C. Cooke, Stephen A. Newby, Josh J. Muller, Christian W. Liu, Ching-Ping James, William H. III Buchanan, Evan G. Lee, Hsiupu D. Zwier, Timothy S. http://hdl.handle.net/1811/38370 2012-12-29T07:18:06Z 2009-01-01T00:00:00Z

CHARACTERIZATION OF STRUCTURAL ISOMERS OF NAPHTHALENE: ELECTRONIC SPECTROSCOPY OF Z-PHENYLVINYLACETYLENE Newby, Josh J.; Muller, Christian W.; Liu, Ching-Ping; James, William H. III; Buchanan, Evan G.; Lee, Hsiupu D.; Zwier, Timothy S. In a variety of contexts from planetary atmospheres to combustion processes, the appearance of C$_{10}$H$_8$ is commonly attributed to naphthalene. Often neglected are other stable C$_{10}$H$_8$ isomers that could be formed prior to isomerization to naphthalene, such as phenylvinylacetylene (PVA, 1-phenyl-1-buten-3-yne). The electronic spectroscopy of the E isomer of PVA has already been reported, \textbf {112}, 9454 (2008).} but direct isomerization to naphthalene would seem more likely from the Z isomer. Here, we report the jet-cooled laser induced fluorescence and single vibronic level dispersed fluorescence spectra of Z-PVA. The spectra display low frequency vibronic structure reminiscent of that in styrene, attributable to the out-of-plane torsion and bend of the vinylacetylene group. The vibrational assignments are assisted by \textit{ab initio} calculations and the results are compared with the analogous motions in styrene. Interestingly, the excitation spectrum shows a dramatic decrease in fluorescence intensity about 600 \wn above the electronic origin. This intensity drop off is attributable to a turn on in nonradiative processes. C. P. Liu, J. J. Newby, C. W. Muller, H. D. Lee, and T. S. Zwier \textit{J. Phys. Chem. A.; Author Institution: Department of Chemistry, Purdue University, West Lafayette, IN 47907

2009-01-01T00:00:00Z Newby, Josh J. Muller, Christian W. Liu, Ching-Ping James, William H. III Buchanan, Evan G. Lee, Hsiupu D. Zwier, Timothy S. Chen, Ziqiu Wijngaarden, Jennifer Van http://hdl.handle.net/1811/38369 2012-12-29T07:44:51Z 2009-01-01T00:00:00Z

FOURIER TRANSFORM MICROWAVE AND INFRARED SPECTROSCOPIC INVESTIGATION OF PROPIOLACTONE Chen, Ziqiu; Wijngaarden, Jennifer Van The pure rotational spectrum of the four-membered ester ring propiolactone (C${_3}$H${_4}$O${_2}$) has been measured in a supersonic jet between 7 and 22 GHz using Fourier transform microwave (FTMW) spectroscopy. For the normal isotopologue, a total of 19 \textit{a-} and \textit{b-}type transitions have been recorded. Fifteen transitions due to three different $^{13}$C isotopologues have also been observed. The microwave spectrum was analyzed to obtain an improved set of ground state rotational constants in comparison to earlier microwave experiments \underline{\textbf{43}} (1190), 1965.}. The new set of rotational parameters was used to predict the rovibrational band structure of the lowest frequency modes of propiolactone. A total of 12 vibrational band origins have been observed between 400 and 1500 cm$^{-1}$ using the far infrared beamline of the Canadian Light Source coupled to a Bruker IFS125HR spectrometer. The spectra were recorded with a resolution of 0.000969 cm$^{-1}$ and although the intensities of the bands vary, 9 bands are of sufficient quality for complete rovibrational assignment. The progress of the assignment of this rich spectrum will be discussed. D. W. Boone, C O. Britt and J. E. Boggs \textit{J. Chem. Phys.; Author Institution: Department of Chemistry, University of Manitoba, Winnipeg MB R3T 2N2 Canada

2009-01-01T00:00:00Z Chen, Ziqiu Wijngaarden, Jennifer Van Pulliam, R. L. Ziurys, L. M. http://hdl.handle.net/1811/38368 2012-12-29T07:44:50Z 2009-01-01T00:00:00Z

THE PURE ROTATIONAL SPECTRUM OF TIS (X$^{3}\Delta_r$) IN ALL THREE SPIN COMPONENTS Pulliam, R. L.; Ziurys, L. M. The pure rotational spectrum of TiS in the X$^{3}\Delta_r$ ground state has been measured using millimeter-wave direct absorption techniques. This species was created by the reaction of hydrogen sulfide gas with titanium vapor produced in a Broida oven which was modified to withstand the extreme temperatures required to melt this metal. Eight transitions have been recorded, each consisting of three spin components. No lambda-doubling was observed, as expected for a $\Delta$ state. The data were fit with a Hund's case(a) Hamiltonian and spectroscopic constants have been determined. The results from this study, as well as a comparison to past optical data will be presented. Author Institution: Department of Chemistry, Department of Astronomy, Steward Observatory, University of Arizona, Tucson, AZ 85721

2009-01-01T00:00:00Z Pulliam, R. L. Ziurys, L. M. Chang, Chih-Hsuan Lopez, Gary V. Johnson, Philip M. Sears, Trevor J. http://hdl.handle.net/1811/38367 2012-12-29T07:44:48Z 2009-01-01T00:00:00Z

SLOW ELECTRON VELOCITY MAPPING FOR THE STUDY OF CATIONIC STATES OF AROMATIC MOLECULES Chang, Chih-Hsuan; Lopez, Gary V.; Johnson, Philip M.; Sears, Trevor J. Slow electron velocity mapping (SEVM), a variant of velocity map imaging (VMI), has been implemented to study the vibronic levels of ionized aromatic molecules. The technique of velocity map imaging has been shown to be a powerful method and has gained enormous impetus since its development by Parker et al. \textbf{68}, 3477 (1997).} SEVM is a versatile photoelectron spectroscopy method that reveals the low energy ionic vibrational structure and also retains the VMI capability to measure angular distributions of the photoelectron. Photoelectron images of the cationic vibrational structure and their angular dependence reflect the character of both the final state and the neutral level from which ionization occurs. Hence, from the photoelectron energies and angular distributions, information on the vibronic character of levels in the first neutral excited state (S1) and the cation state (D0) of molecules can be obtained by resonantly enhanced multiphoton ionization (REMPI). Phenylacetylene (PA) and fluorene were studied and probed using REMPI excitation schemes and the SEVM technique. In the case of PA, the angular distribution of the electrons correlated with ioization \textit{via} the 6a mode involving the breathing of the benzene ring shows a distinct mode-dependent effect, illustrating the technique. However, in the case of fluorene, only the vibrationless level and stretching vibrational modes in the cation state showed Franck-Condon activity and had nearly isotropic photoelectron distributions. Future work on polycyclic aromatic hydrocarbon systems related to fluorene, such as carbazole, dibenzofuran, and dibenzothiophene is planned. Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A.~T.~J.~B. Eppink and D.~H. Parker \textit{Rev.~Sci.~Instrum.; Author Institution: Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973; Department of Chemistry, Stony Brook University, Stony Brook, New York 11794; Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973 and Department of Chemistry, Stony Brook University, Stony Brook, New York 11794

2009-01-01T00:00:00Z Chang, Chih-Hsuan Lopez, Gary V. Johnson, Philip M. Sears, Trevor J. Dixneuf, Sophie Ruth, Andy A. Vaughan, Stewart Varma, Ravi M. Orphal, Johannes http://hdl.handle.net/1811/38366 2012-12-29T07:44:58Z 2009-01-01T00:00:00Z

TIME-DEPENDENT EMISSION OF MOLECULAR IODINE FROM BROWN SEAWEED: AN APPLICATION OF INCOHERENT BROADBAND CAVITY-ENHANCED ABSORPTION SPECTROSCOPY Dixneuf, Sophie; Ruth, Andy A.; Vaughan, Stewart; Varma, Ravi M.; Orphal, Johannes A large variety of gases enters the atmosphere from seawater and is the driving force of local and global atmospheric processes. Since knowing the composition of gases evolving from the sea and the total fluxes involved is a precondition for the development of quantitative atmospheric models, sea-to-air exchange mechanisms are subject of intense investigation. The release of volatile organic iodine compounds and of molecular iodine (I$_{2}$) into the marine boundary layer is recognized to be of fundamental importance for (subsequent) ozone depletion events and marine aerosol formation, which in turn affects global radiative forcing. Although biogenic emission (iodovolatilization) of I$_{2}$ by phytoplankton in open waters and via macrophytic algae in coastal areas, has been suggested to be one of the most important processes leading to the observed iodine concentrations in the marine troposphere, the dominant sources of molecular iodine and in particular the mechanisms of I$_{2}$ release are still being debated. We used incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) for the first quasi in situ detection of molecular iodine after emission from the brown macroalgae, \textit{Laminaria digitata}, under naturally occurring stress. Since IBBCEAS combines a high spatial and temporal resolution with high molecule-specific detection sensitivity it is ideally suited to study point sources of atmospheric trace constituents. In this context IBBCEAS complements long-path DOAS setups in the search for trace gas emission sources. In this presentation we will show that the release of I$_{2}$ occurs in short, regularly occurring, strong bursts. The new data suggest that the control of I$_{2}$ release by the plant may be based on a nonlinear reaction scheme involving the release of H$_{2}$O$_{2}$ on the plant s surface, leading to quasi-oscillatory emission behaviour. Preliminary measurement of flux estimates of I$_{2}$ release per kg of dry weight of the plant will be discussed. Author Institution: Laser Spectroscopy Group, Physics Department, University College Cork, Ireland; School of Chemistry, University of Leeds, United Kingdom; Laser Spectroscopy Group, Physics Department, University College Cork, Cork, Ireland; Laboratoire Inter-universitaire des Systemes Atmospheriques, Universite Paris XII, Creteil, France

2009-01-01T00:00:00Z Dixneuf, Sophie Ruth, Andy A. Vaughan, Stewart Varma, Ravi M. Orphal, Johannes Kang, Lu Gharaibeh, Mohammed A. Clouthier, Dennis J. Novick, Stewart E. http://hdl.handle.net/1811/38365 2009-07-30T06:17:13Z 2009-01-01T00:00:00Z

MICROWAVE SPECTROSCOPY OF THE HEAVY-ATOM CARBENE ANALOGS: HSiI and DSiI Kang, Lu; Gharaibeh, Mohammed A.; Clouthier, Dennis J.; Novick, Stewart E. The pure rotational spectra of 6 silicon isotopologues, of HSiI and of DSiI have been recorded in natural abundance by pulsed-jet Fourier transform microwave (FTMW) spectroscopy. Neon was passed over dry ice cooled H$_3$SiI or D$_3$SiI and introduced into the pulsed valve of the FTMW spectrometer. The HSiI and the DSiI were produced in-situ with a 1000 V DC-discharge nozzle. Only $a$-type transitions can be observed from 6 - 26 GHz; $K_a$ = 0 transitions for the HSiI and $K_a$ = 0 and 1 transitions for the DSiI isotopologues. All observed transitions were assigned unambiguously. The molecular structure and chemical bonding of this heavy atom carbene will be discussed. Author Institution: Department of Natural Sciences, Union College, Barbourville, KY 40906; Department of Chemistry, University of Kentucky, Lexington, KY 40506; Department of Chemistry, Wesleyan University, Middletown, CT 06459

2009-01-01T00:00:00Z Kang, Lu Gharaibeh, Mohammed A. Clouthier, Dennis J. Novick, Stewart E. Afshari, Mahin Dehghany, M. Oliaee, J. N. Moazzen-Ahmadi, N. McKellar, A. R. W. http://hdl.handle.net/1811/38364 2012-12-29T07:44:54Z 2009-01-01T00:00:00Z

INFRARED SPECTRA OF TWO ISOMERS OF THE OCS-C$_2$H$_2$ AND OCS-C$_2$D$_2$ Afshari, Mahin; Dehghany, M.; Oliaee, J. N.; Moazzen-Ahmadi, N.; McKellar, A. R. W. Spectra of the weakly-bound OCS-C$_2$H$_2$ and OCS-C$_2$D$_2$ complexes in the region of the OCS \nub{1} fundamental ($\sim$2062 \wn) are observed in a pulsed supersonic slit jet expansion probed with a tunable diode laser. For each complex two bands are observed and assigned to the near parallel and the T-shape isomers. The ground state rotational and centrifugal distortion parameters were previousely determined from microwave studies. \textbf{103}, 3884 (1999).} \textbf{312}, 357 (1999).} Analysis of the infrared spectra gives accurate band origins as well as rotational and centrifugal distortion parameters for the upper states. All four bands show a red shift with respect to the monomer band origin, with the T-shape isomers having about 5.4 \wn larger shift than the corresponding near parallel isomers. S.A. Peebles and R.L. Kuczkowski, \textit{J. Phys. Chem. AS.A. Peebles and R.L. Kuczkowski, \textit{Chem. Phys. Lett.; Author Institution: Department of Physics and Astronomy, University of Calgary; Calgary, AB T2N 1N4, Canada; Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada

2009-01-01T00:00:00Z Afshari, Mahin Dehghany, M. Oliaee, J. N. Moazzen-Ahmadi, N. McKellar, A. R. W. Khistyaev, K. Krylov, A. I. Landau, A. http://hdl.handle.net/1811/38363 2012-12-29T07:44:56Z 2009-01-01T00:00:00Z

ELECTRONIC STRUCTURE OF N$_2$ DIMER CATION Khistyaev, K.; Krylov, A. I.; Landau, A. Energies of the ground and the lowest excited states of the N$_2$ dimer cation were calculated. EOM-IP-CCSD method was used for calculations. The goal of this study was to explain experimental data of N$_2$ dimer dissociation following charge-exchange between nitrogen dimer cation and Cs from R. Continetti group. This system is also very interesting from the theoretical point of view because of the unusual electronic structure and as a model charge-transfer system. We characterized the bonding of the ionized system due to orbital overlaps between the fragments. To extend EOM-IP-CCSD to large systems, frozen natural orbitals approach can be employed. Benchmark results demonstrating the performance of EOM-IP-CCSD/FNO scheme will be presented. We found that for closed shell molecules the orbital space can be reduced by 40\% with minor effect on the ionization energy at EOM-IP-CCSD level (the minimal absolute errors are about 1 kcal/mol). Author Institution: Department of Chemistry, University of Southern California, Los Angeles, CA 90089

2009-01-01T00:00:00Z Khistyaev, K. Krylov, A. I. Landau, A. Takematsu, Kana Eddingsaas, Nathan Okumura, Mitchio Stanton, John http://hdl.handle.net/1811/38362 2009-07-30T06:17:04Z 2009-01-01T00:00:00Z

THE JAHN-TELLER (JT) EFFECT IN THE $\widetilde{A}$ STATE OF THE NITRATE RADICAL NO$_3$ Takematsu, Kana; Eddingsaas, Nathan; Okumura, Mitchio; Stanton, John The JT effect in the $\widetilde{A}$$^2$E$^{\prime \prime}$ of NO$_3$ is poorly understood. A preliminary spectrum of the vibronically-allowed $\widetilde{A}$$\leftarrow$$\widetilde{X}$ transition, coupled with ab initio calculations, shows moderate JT activity in the $\widetilde{A}$ state. Vibronic bands exhibit either static or dynamic JT distortions depending on the vibrational level of the upper $\widetilde{A}$ state. The picture of the $\widetilde{A}$ state is however incomplete. For example, in the E$^{\prime \prime}$$\otimes$e$^{\prime}$=a$_1$$^{\prime \prime}$$\oplus$a$_2$$^{\prime \prime}$$\oplus$e$^{\prime \prime}$ manifold, while the splitting would provide a direct measure of the JT strength, only the a$_1$$^{\prime \prime}$ levels have been observed. We have gained new insight into the $\widetilde{A}$ state by examining the hot bands of NO$_3$ which access previously unobserved dark levels of the $\widetilde{A}$ state. Author Institution: Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125; Department of Chemistry, University of Texas at Austin, Austin, TX 78712

2009-01-01T00:00:00Z Takematsu, Kana Eddingsaas, Nathan Okumura, Mitchio Stanton, John Dick, Michael J. Drouin, Brian J. Pearson, John C. http://hdl.handle.net/1811/38361 2009-07-30T06:16:57Z 2009-01-01T00:00:00Z

PRESSURE BROADENING OF SEVERAL TERAHERTZ TRANSITIONS OF WATER FROM 20K TO 200K Dick, Michael J.; Drouin, Brian J.; Pearson, John C. The pressure broadening of the 0$_{00}$ to 1$_{11}$, 1$_{11}$ to 2$_{02}$, 3$_{03}$ to 3$_{12}$, 2$_{21}$ to 3$_{12}$ and 3$_{12}$ to 3$_{21}$ transitions of water by hydrogen and helium has been investigated using the collisional cooling technique. This technique has allowed the broadening to be examined over the temperature range of 20K to 200K, far below the freezing point of water. The results of the investigation show a general trend of two distinct regions of broadening for each rotational line. Above 50K, the temperature dependence of the broadening follows the expected power law behavior. Below 50K, the broadening decreases very rapidly with temperature. This behavior is similar to that observed in a recent study of the pressure broadening of the 556 GHz line of water completed in our lab. However, this behavior is in sharp contrast to that predicted by previous theoretical calculations. \\ \\ We will present the results of our current investigation. This will include a discussion comparing the current study with the results of the previous experimental and theoretical work. The pressure broadening is a window into the collisional excitation and the implications of our results for the interpretation of water spectra in the interstellar medium will be discussed. Author Institution: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109

2009-01-01T00:00:00Z Dick, Michael J. Drouin, Brian J. Pearson, John C. Shubert, V. Alvin Muller, Christian W. James, William H. III Zwier, Timothy S. http://hdl.handle.net/1811/38360 2012-12-29T07:44:55Z 2009-01-01T00:00:00Z

WATER'S ROLE IN RESHAPING A MACROCYCLE'S BINDING POCKET: CONFORMATION-SPECIFIC INFRARED AND ULTRAVIOLET SPECTROSCOPY OF BENZO-15-CROWN-5-$(\mathrm{H}_{2}\mathrm{O})_{n}$-CLUSTERS $(n$\,$=$\,$1,\,2)$ Shubert, V. Alvin; Muller, Christian W.; James, William H. III; Zwier, Timothy S. \begin{wrapfigure}{r}[0cm]{3.5cm} \vspace{-2.0cm} \hspace*{-1.7cm} \epsfig{width=0.4\textwidth,file=B15C-W2-test.eps} \end{wrapfigure} Crown ethers are well-studied examples of flexible macrocycles with a high binding selectivity for substrates, especially cations. We investigated the conformational preferences of the singly and doubly complexed water clusters of the crown ethers benzo-15-crown-5~(B15C) and its amino-derivative 4'-aminobenzo-15-crown-5~(ABC) cooled in a supersonic jet expansion. The fluorescence excitation, resonance enhanced two-photon ionization (R2PI), UV-UV holeburning (UVHB), fluorescence-dip infrared (FDIR), resonant ion-dip infrared (RIDIR) and novel IR-IR-UV holeburning$^{1}$ spectra allowed for the identification of two $\mathrm{B}15\mathrm{C}$--$(\mathrm{H}_{2}\mathrm{O})_{1}$ conformers and one $\mathrm{ABC}$--$(\mathrm{H}_{2}\mathrm{O})_{1}$ conformer. These conformers are characterized by an all-planar arrangement of the atoms directly bound to the benzene ring in which the crown ether macrocycle opens up to a symmetric structure and accomodates a doubly and triply H-bonded $\mathrm{H}_{2}\mathrm{O}$ molecule in two distinct ways, respectively. Two $\mathrm{B}15\mathrm{C}$--$(\mathrm{H}_{2}\mathrm{O})_{2}$ conformers and one $\mathrm{ABC}$--$(\mathrm{H}_{2}\mathrm{O})_{2}$ conformer were identified. One of the $\mathrm{B}15\mathrm{C}$--$(\mathrm{H}_{2}\mathrm{O})_{2}$ conformers contains a macrocycle configuration identical to that found in the monohydrated clusters with an H-bonding topology in which the $\mathrm{H}_{2}\mathrm{O}$ molecules occupy both available sites simultaneously. The second $\mathrm{B}15\mathrm{C}$--$(\mathrm{H}_{2}\mathrm{O})_{2}$ conformer is assigned to an H-bond pattern in which the two $\mathrm{H}_{2}\mathrm{O}$ molecules are concatenated to form an H-bonded bridge involving only three of the four available O--H-bonds~(see figure). \vspace*{0.2cm} (1) V.~A. Shubert and T.~S.~Zwier, \textit{J. Phys. Chem.~A}, \textbf{2007}, \textit{111}, 13283. Author Institution: Argonne National Laboratory, Chemical Sciences and Engineering; Division, 9700 South Cass Avenue, Argonne, IL 60439; Department of Chemistry, Purdue University, West Lafayette, IN 47907-2084

2009-01-01T00:00:00Z Shubert, V. Alvin Muller, Christian W. James, William H. III Zwier, Timothy S. Fehnel, Robert R. Lehmann, Kevin K. http://hdl.handle.net/1811/38359 2012-12-29T07:44:55Z 2009-01-01T00:00:00Z

HENDI SPECTROSCOPY OF C-H STRETCHING MODES OF METHANE AND SUBSTITUTED METHANE MOLECULES Fehnel, Robert R.; Lehmann, Kevin K. We report the first results with a new Helium Nanodroplet Isolation Spectroscopy machine at UVa. The excitation source is an ARGOS cw PPLN OPO (Aculight). which produces $\sim$2 W in the 3.2-3.9 $\mu$m spectral window. We are extending the spectroscopy of methane in helium, having observed weak, Fermi Resonance induced ro-vibrational transitions of CH$_4$ and the C-H fundamentals of CH$_3$D, CH$_2$D$_2$, and CHD$_3$. We have also observed the spectrum of CH$_3$Cl and plan to report on other substituted methane molecules at the conference. Author Institution: Department of Chemistry, University of Virginia, Charlottesville VA, 22904-4319

2009-01-01T00:00:00Z Fehnel, Robert R. Lehmann, Kevin K. Weigum, Natalie McElcheran, Clare Walker, Kaley A. Taylor, Jeffrey R. Boone, Chris Bernath, Peter F. Toon, Geoffrey C. Manney, Gloria Strahan, Susan Duncan, Bryan Yoshida, Yasuko Wang, Yuahng http://hdl.handle.net/1811/38358 2009-07-30T06:16:10Z 2009-01-01T00:00:00Z

GLOBAL METHYL CHLORIDE MEASUREMENTS FROM THE ACE-FTS INSTRUMENT Weigum, Natalie; McElcheran, Clare; Walker, Kaley A.; Taylor, Jeffrey R.; Boone, Chris; Bernath, Peter F.; Toon, Geoffrey C.; Manney, Gloria; Strahan, Susan; Duncan, Bryan; Yoshida, Yasuko; Wang, Yuahng One of the most abundant chlorine-containing molecules in the atmosphere is methyl chloride; a species whose sources are almost entirely natural. The most common sources of methyl chloride are tropical plants, senescent or dead leaves and biomass burning. As the impacts of the Montreal Protocol and its subsequent amendments are becoming apparent in the reduction of chlorofluorocarbons in the atmosphere, naturally-produced methyl chloride is playing an increasingly significant role in the atmospheric ozone budget.\\ \\While much is known about the concentration of methyl chloride at ground level, there are relatively few measurements of its altitude distribution. Solar occultation profiles from the Atmospheric Chemistry Experiment (ACE) satellite mission have been used to produce the first study of the global distribution of methyl chloride in the upper troposphere and stratosphere. Measurements from the infrared Fourier transform spectrometer (ACE-FTS) on board ACE, collected over three years from February 2004 to March 2007, were used in the analysis. These results were compared with results from the MkIV balloon-borne Fourier transform spectrometer, the Global Modelling Initiative\Õs (GMI) combination troposphere and stratosphere model and the GEOS-Chem troposphere model. This paper will discuss the challenges of retrieving methyl chloride from atmospheric spectra. Also, it will discuss the differences between the global methyl chloride distribution as determined from the ACE-FTS and the MkIV FTIR measurements and the GMI and GEOS-Chem models. \\ Author Institution: Department of Physics, University of Toronto, Toronto, Ontario; Canada M5S 1A7; Department of Chemistry, University of Waterloo, Waterloo, Ontario; Canada N2L 3G1; Jet Propulsion Laboratory, Pasadena, CA 91109, USA; Goddard Earth Science and Technology Center, University of Maryland, Baltimore County, Baltimore, MD 21250, USA; School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA USA

2009-01-01T00:00:00Z Weigum, Natalie McElcheran, Clare Walker, Kaley A. Taylor, Jeffrey R. Boone, Chris Bernath, Peter F. Toon, Geoffrey C. Manney, Gloria Strahan, Susan Duncan, Bryan Yoshida, Yasuko Wang, Yuahng Giuliano, Barbara M. Maris, Assimo Melandri, Sonia Favero, Laura B. Evangelisti, Luca Caminati, Walther http://hdl.handle.net/1811/38357 2012-12-29T07:45:08Z 2009-01-01T00:00:00Z

PROTON DONOR/ACCEPTOR PROPENSITIES OF AMMONIA: ROTATIONAL STUDIES OF ITS MOLECULAR COMPLEXES WITH ORGANIC MOLECULES Giuliano, Barbara M.; Maris, Assimo; Melandri, Sonia; Favero, Laura B.; Evangelisti, Luca; Caminati, Walther We studied the rotational spectra of the adducts of ammonia with several organic molecules, namely \textit{tert}-butanol,, 2008, 463, 330} glycidol,, 2009, 48, 1102} ethyl alcohol, anisol and 1,4-difluorobenzene. The adducts with glycidol and ethanol have been observed for both conformers of the substrate molecule. Based on the rotational and $^{14}$N quadrupole coupling constants of the various complexes, we found a considerably different behaviour of ammonia, with respect to water, in its proton donor/acceptor double role. In the interaction with the three alcohol molecules, NH$_{3}$ acts as a proton acceptor and the OH groups as a proton donor. However, in the case of glycidol-NH$_{3}$, a secundary N-H$\cdots$O interaction occurrs between ammonia and the ether oxygen. This interaction generates a sizable \textit{V}$_{3}$ barrier to the internal rotation of the NH$_{3}$ moiety, while NH$_{3}$ undergoes a free rotation in \textit{tert}-butanol-NH$_{3}$ and in ethanol-NH$_{3}$. As to the anisole-NH$_{3}$ and 1,4-difluorobenzene-NH$_{3}$ complexes, the NH$_{3}$ group explicits its double proton donor/acceptor role, although through two weak (C$_{Me}$-H$\cdots$N and N-H$\cdots\pi$) H-bonds. There is, however, an important difference between the two complexes, because in the first one NH$_{3}$ lies out of the aromatic plane, while in the second one it is in the plane of the aromatic ring. B.~M.~Giuliano, M.~C.~Castrovilli, A.~Maris, S.~Melandri, W.~Caminati and E.~A.~Cohen, \textit{Chem.Phys.Lett.B.~M.~Giuliano, S.~Melandri, A.~Maris, L.~B.~Favero and W.~Caminati, \textit{Angew.Chem.Int.Ed.; Author Institution: Dipartimento di Chimica "G. Ciamician" dell'Universita, Via Selmi 2, I-40126 Bologna, Italy

2009-01-01T00:00:00Z Giuliano, Barbara M. Maris, Assimo Melandri, Sonia Favero, Laura B. Evangelisti, Luca Caminati, Walther Lear, Benjamin J. Chisholm, Malcolm H. http://hdl.handle.net/1811/38356 2012-12-29T07:45:07Z 2009-01-01T00:00:00Z

EVOLUTION OF THE MLCT BAND FOLLOWING CHANGES IN OXIDATION STATE FOR HIGHLY COUPLED MIXED VALENCE COMPLEXES Lear, Benjamin J.; Chisholm, Malcolm H. The MLCT band for a series of dimers composed of pairs of quadruply bonded metal-metal units ([MM(CH$_3$CO$_2$)$_3$]$_2$-$\mu_2$-oxalate; where M=Mo or W) is examined in both the neutral and +1 (mixed valence) states. The MLCT band for the neutral state of these complexes exhibits clear vibronic features that are greatly reduced in intensity upon generation of the mixed valence state. Utilizing the time dependent theory of spectroscopy as developed by Eric Heller, these results (together with Raman spectra and TD-DFT calculations) are used in order to draw conclusions concerning the potential energy surfaces involved in the MLCT transition for these complexes. In particular, we are concerned with changes to the offset of the ground and excited state potential energy surfaces that occur along the coordinates involved in the vibronic coupling and which accompany changes in oxidation state. The insight thus gained is used in order to understand the degree of electronic coupling present in mixed valence species and to comment on the classification of mixed valence complexes. Author Institution: The Ohio State University, Department of Chemistry, Columbus, Ohio 43210

2009-01-01T00:00:00Z Lear, Benjamin J. Chisholm, Malcolm H.