Abstracts of OSU International Symposium on Molecular Spectroscopy 1980-1989

THE ROTATIONAL RKR METHOD

Nesbitt, David J. — 1988-01-01T00:00:00Z

THE ROTATIONAL RKR METHOD Nesbitt, David J.; Child, Mark S. In the rapidly growing field of high resolution infrared spectroscopy of van der Waals complexes, one often obtains a wealth of rotational information for a single vibrational state. A new RKR based Method is described for extracting one dimensional potentials via inversion of high precision data on rotational energy levels alone. This method proves remarkably successful at quantitatively reproducing intermolecular potentials from rotational data for I) weakly bound (e.g. model van der Waals complexes) and ii) strongly bound (e.g. $v-O$ rotational levels of $H_{2} X^{1}\Sigma_{g})$ molecules. $^{1}$ M. S. Child and D. J. Nesbitt, Chem. Phys. Lett. (in press).; Author Institution: Joint Institute for Laboratory Astrophysics, National Bureau of Standards and University of Colorado at Boulder

LASER-INDUCED FLUORESCENCE STUDIES OF THE A-X AND B-X SYSTEMS OF THE NCO RADICAL

Sullivan, Brian J. — 1982-01-01T00:00:00Z

LASER-INDUCED FLUORESCENCE STUDIES OF THE A-X AND B-X SYSTEMS OF THE NCO RADICAL Sullivan, Brian J.; Smith, Gregory P.; Crosley, David R. NCO was produced in a low-pressure flow system by reacting HNCO with F atoms generated in a discharge in $CF_{4}/He$. Utilizing a Nd:YAG-pumped dye laser, excitation spectra of the $A^{2}\Sigma^{+}-X^{2}\Pi_{1}$ system and the $B^{2}\Pi_{1}-X^{2}\Pi_{1}$ system were obtained between $4400-3980 \AA$ and $3156-3142 \AA$ respectively. Signals were read out using a boxear intergrator, which was operated in a scanning mode for lifetime runs. A small monochromator, capable of $1 \AA$ resolution, was used to obtain fluorescence spectra. Five vibrational levels (0,0,0; 0,1,0; 1,0,0; 0,2,0; 0,0,1) of the A state were probed, and assignments could be made following Dixon (1). The radiative lifetime was found to be 410 nsec and was insensitive to vibrational level. Quenching rates determined for $N_{2}$ and $O_{2}$ are $3.0 \times 10^{-11}$ and $11 \times 10^{-11} cm^{3} \sec^{-1}$ respectively. The $R_{1}$ and $R_{2}$ heads of the (0,0,0,-0,0,0) band of the B-X system (2) were pumped, and the resulting fluorescence spectra showed a long Progression in ground state stretching modes. These spectra allowed us to extract a set of constants describing these stretching vibrations in $X^{2}\Pi_{1}$: $ \begin{array}{lll} \omega^{0}_{1}=1286 cm^{-1} & \omega^{0}_{3}=1925 cm^{-1} & X_{13} = 27.8 cm^{-1}\\ X_{11}=-10.3 cm^{-1} & X_{33}=-11.6 cm^{-1}& \end{array} $ The radiative lifetime obtained for the 8 state was 63 nsec. Quenching rates for $N_{2}$ and $O_{2}$ were found to be $1.3\times 10^{-10}$ and $2.0\times 10^{-10} cm^{3} \sec^{-1}$ respectively. $^{(1)}$R.N.Dixon, Phil. Trans. Roy. Soc. London, A262, 165 (1960). $^{(2)}$R.N. Dixon, Can. J. Phys. 38, 10 (1960). This work was supported by the U. S. Army Research Office.

LASER INDUCED FLUORESCENCE FROM DISSOCIATIVE AND PREDISSOCIATIVE STATES OF OZONE

Imry, D. — 1982-01-01T00:00:00Z

LASER INDUCED FLUORESCENCE FROM DISSOCIATIVE AND PREDISSOCIATIVE STATES OF OZONE Imry, D.; Katayama, D. H.; Kinsey, J. L.; Field, R. W. Laser induced fluorescent (LIF) from bound states of molecules is well known but LIF from dissociative states such as the upper electronic state of the Huggins bands and Hartley continuum of ozone has not been reported previously. Recently, we used the fourth harmonic of a Nd:YAG laser at 266 nm to excite the Hartley continuum and observed the dispersed fluorescence which clearly showed vibrational structure for the ground state of ozone. We have also obtained the excitation spectrum for a number of Huggins bands by using a tunable dye laser pumped by the Nd:YAG laser. We will discuss the ozone ground state spectrum which shows vibrational structure unreported previously and show that information on the dissociative state can be obtained by this technique.

PHOTODISSOCIATION OF OZONE AT 248 nm

Wine, P. H. — 1982-01-01T00:00:00Z

PHOTODISSOCIATION OF OZONE AT 248 nm Wine, P. H.; Ravishankara, A. R. Excitation of $O_{3}$ in the strong Hartley absorption band centered at 255 nm results in dissociation via two energetically and spin allowed channels: [FIGURE]. The branching ratio for production of ground state and electronically excited oxygen atoms is required for understanding ozone spectroscopy and photochemistry, and is a critical parameter in models of atmospheric chemistry. We have monitored $O(^{3}P_{J})$ using time resolved resonance fluorescence detection following 248 nm laser photolysis of $O_{3}/He$ and $O_{3}/He/R$ mixtures $(R = N_{2}, CH_{4})$. From these data, the fraction of photodissociation events leading to the production of $O(^{3}P_{J})$, i.e., $\Phi [O(^{3}P_{j})]/\Phi[O(^{1}D_{2})]$. has been determined to be $.103 \pm .131$. This result will be compared with data from other laboratories and its spectroscopic and photochemical implications will be discussed.

LASER MAGNETIC RESONANCE SPECTRUM OF THE $\nu _{2}$ BAND OF $AsH_{2}^{\ast}$

Muenchausen, R. E. — 1982-01-01T00:00:00Z

LASER MAGNETIC RESONANCE SPECTRUM OF THE $\nu _{2}$ BAND OF $AsH_{2}^{\ast}$ Muenchausen, R. E.; McCoy, W. J.; Hills, G. W. The $\nu_{2}$ bending mode of the $AsH_{2}$ radical in the $\tilde{X}^{2}B_{1}$ state has been investigated using $CO_{2}$ laser magnetic resonance spectroscopy. A large number of resonances have been observed in the $920-1070 cm^{-1}$ region. Many resonances show the characteristic quarters of resolved $^{75}As (T=3/2)$ hyperline structure. The $AsH_{2}$ radical was produced in a discharge flow system by adding to arsine $(AsH_{3})$ the products of a microwave discharge of $H_{2}$ in Ar. The current evidence for the active species as $AsH_{2}$ is mainly chemical. The results of the spectrum assignment and parameter determination, currently underway, should confirm the identity. $^{\ast}$Research supported by the ACS-PRF

MICROWAVE STUDIES OF $\tilde{A}$, NHD AND $\tilde{X}, ND_{2}$ USING MICROWAVE OPTICAL DOUBLE RESONANCE

Brown, J. M. — 1982-01-01T00:00:00Z

MICROWAVE STUDIES OF $\tilde{A}$, NHD AND $\tilde{X}, ND_{2}$ USING MICROWAVE OPTICAL DOUBLE RESONANCE Brown, J. M.; Cook, J. M.; Hills, G. W. Microwave optical double resonance spectroscopy has been used to study microwave transitions in the 1.5 CHz-12.4 CHz spectral region for both NHD and $ND_{2}$. The studies of NHD have focussed on determining magnetic hyperfine coupling constants for $^{14}N$ and $^{1}H (^{2}D)$ in the $\Pi(0, 10, 0)$ and (0, 10, 0) vibration states of the $\tilde{A} {^{2}A^{1}}$ state. Over 100 hyperfine components involving 11 magnetic dipole transitions of the type, $^{N}K_{a}K_{C}, J-N-1_{2} \leftrightarrow J-N + 1_{2}$, and one electric dipole transition. $2_{20}, F_{1} \leftrightarrow 2_{21}$. $F_{2}\Delta (0, 11, 0)$, have been observed. For $ND_{2}$, over 200 microwave transitions, all of the magnetic dipole type, were observed from 21 rotational states in (0, 0, 0) of $\tilde{X} B_{1}$. The chief motivation behind the work was to determine accurate spin-rotation and spin-rotational centrifugal distortion constants. $^{\ast}$Research supported by Research Corporation and the National Science Foundation

MICROWAVE OPTICAL DOUBLE RESONANCE SPECTROSCOPY USED AS AN ASSIGNMENT METHOD IN OPTICAL $SPECTROSCOPY^{\ast}$

Hills, G. W. — 1982-01-01T00:00:00Z

MICROWAVE OPTICAL DOUBLE RESONANCE SPECTROSCOPY USED AS AN ASSIGNMENT METHOD IN OPTICAL $SPECTROSCOPY^{\ast}$ Hills, G. W. In microwave optical double resonance spectroscopy (MODR) the primary interest is generally in the accurate measurement of the microwave adsorption frequencies. In the work described here though, known microwave transitional frequencies are pumped and the optical transitions frequency of the dye laser is swept. MODR signals are seen in both 3-level and 4-level (collisional) schemes. The method has been applied to $NH_{2}$ on the $1_{10}, J-1/2, \Pi(0, 10, 0) \leftrightarrow u$ transition around $6.3 CHz^{1}$. Double resonance signals were observed for many known ortho levels in $\Pi(0, 10, 0) (N < 7), \Phi(0, 10, 0), \Phi (1, 6, 0)$ etc. Two levels (presumably) responsible for a perturbation to $1_{10}, \Pi(0, 10, 0), (F_{1} and F_{2})$, were located. In the ``u'' manifold of states, $F_{1}$ and $F_{2}$ components of rotational levels with $N-2, K_{a}-2$ and $N-3, K_{a}-2$ were observed. Attempts at a vibronic assignment of the u manifold have so far been unsuccessful. Application of the method to other molecules may be described. $^{1}$R.S.Lowe et al, J. Chem. Phys. 70, 3359 (1979), $^{\ast}$Research supported by Research Corporation and the National Science Foundation.

STIMULATED EMISSION PUMPING OF HIGHLY EXCITED VIBRATIONAL LEVELS OF $\tilde{\chi} ^{1}A_{1} H_{2}CO$

Reisner, D. E. — 1982-01-01T00:00:00Z

STIMULATED EMISSION PUMPING OF HIGHLY EXCITED VIBRATIONAL LEVELS OF $\tilde{\chi} ^{1}A_{1} H_{2}CO$ Reisner, D. E.; Dai, H. L.; Vaccaro, P. H.; Kittrell, C.; Kinsey, J. L.; Field, R. W. Stimulated Emission Pumping (SEP), a double resonance technique, has been developed as a means to probe highly excited vibrational levels of ground electronic states of polyatomic molecules, We report initial experiments on $H_{2}CO$ in a static cell. A PUMP laser populates a known level $(4^{1}_{0} transition)$ or the $\tilde{A} {^{1}A_{2}}$ state. A subsequent DUMP laser stimulates emission downward to vibrational levels of the $\tilde{\chi} {^{1}A_{1}}$ state. Combination levels in both the out-of-plane bend $(v_{4}=4)$ and the C-O stretch $(v_{2}=3)$ have been reached via the $4^{1}_{4}$ and $2^{0}_{3}4^{1}_{0}$ transitions respectively.

ANALYSIS OF THE 5800 \AA SCHUSTER BAND OF THE $ND_{4}$ RADICAL

Herzberg, G. — 1982-01-01T00:00:00Z

ANALYSIS OF THE 5800 \AA SCHUSTER BAND OF THE $ND_{4}$ RADICAL Herzberg, G.; Hougen, Jon T. An emission system first observed over a hundred years ago by Schuster in various DC discharges in flowing $NH_{3}$ has been restudied at the NRC in Ottawa, where mixed isotopic spectra using both D and $^{15}N$ allowed the carrier of the spectrum to be positively $identified^{1}$ as $NH_{4}$. The results of ab initio $calculations^{2}$ and a preliminary rotational $analysis^{1}$ led to a provisional assignment of one hand as a $(3d)^{2}F_{2} - (3s)^{2}A_{1}$ Rydberg transition, even though such a transition would be parity forbidden in the united atom limit. The present work attempts to place the original rotational analysis on a more quantitative basis. A computer program at l'Universite de Dijon, France, originally $developed^{3}$ for vibrational transitions in tatrahedral molecules, was used to carry out a least squares fit of the rotational structure of the observed electronic transition in $NH_{4}$. Group theoretical arguments alone permit the Dijon rotation-vibration Hamiltonian to be used as a phenomenological rotation-electronic Hamiltonian. However, while the precise meaning of the various scalar and tensor operators in the Dijon $formalism^{3}$ is well understood for the rotation-vibration problem in $CH_{4}$, the significance of these parameters for the rotation-electronic problem in $NH_{4}$ has yet to be determined. Various theoretical points and the status of the least squares fit will be discussed. $^{1}$ G. Herzberg, Faraday Disc. Chem. Soc. 71, 165-173 (1981) $^{2}$H.F. King and S. Havriliak, private communication $^{3}$J.P. Champion and G. Pierre, J. Mol. Spectrosc. 79, 255-280 (1980)

BANDS OF THE 2400 \AA SYSTEM OF ACETYLENE.

Watson, J. K. G. — 1982-01-01T00:00:00Z

BANDS OF THE 2400 \AA SYSTEM OF ACETYLENE. Watson, J. K. G.; Herman, M.; Van Craen, J. C.; Colin, R. Detailed assignments of the longer wavelength bands of the $2400 \AA$ absorption system $A^{-1}A_{\mu}(C_{2h})-\tilde{X}^{1}\Sigma^{+}_{g}(D_{\omega h})$ of acetylens $(C_{2}H_{2})$ have been performed, including revisions of some subband assignments. The wavenumbers of the lines of the stronger bands have been fitted simultaneously employing a linear molecule Hamiltonian for the lower electronic state, with inclusion of $\ell$-doubling and $\ell$-resonance effecta in the lavels of the $\pi_{g}$ vibration $\upsilon_{4}$ for $\upsilon_{\Delta} \epsilon 4$, and an asymmetric top Hamiltonian with centrifugal distortion for the upper electronic state. The relative intensities of different subbands, including the effects of axis-switching, will be discussed. The observed vibrational levels of the upper state below $2500 cm^{-1}$ are fairly regular, Estimates of the unobserved fundamentals will be presented. The analysis will be continued to higher vibrational levels, where quasilinear effects should become important.

EMISSION SPECTRUM OF TRITIATED ACETYLENE

Schmieder, R. W. — 1982-01-01T00:00:00Z

EMISSION SPECTRUM OF TRITIATED ACETYLENE Schmieder, R. W. The spectrum of visible emission from tritiated acetylene gas in closed cell with no external excitation has been recorded. Two forms of gas were used: (1) $C_{2}HT$, synthesized by a modified Wilzbach process and mixed with $C_{2}H_{2}$: (2) mixtures of $C_{2}H_{2}$ and $T_{2}$. The gases were held in stainless steel cells of about $20 cm^{3}$ volume with sapphire windows. Pressures were 100-300 Torr. Emitted photons were analyzed with a 1/2-m monochromator, an RCA 31034A-12 photomultiplier, and standard counting electronics. The spectra exhibit the well-known Swan bands of $C_{2}$ and a broad band which may be $C_{2}H$. The CH 431.5 nm band was not prominent. The emission results entirely from the radioactivity of the gas. The energy of the fast beta produced in the tritium decay $T_{+}^{3}He^{+} + \beta^{-} +\upsilon^{-}$ is collisionally degraded in a variety of secondary processes. The observed spectrum can be understood only by examination of the complete degradation energy spectrum.

HIGH RESOLUTION OBSERVATIONS OF LASER EXCITED FLUORESCENCE IN $NO_{2}$

Hardwick, J. H. — 1982-01-01T00:00:00Z

HIGH RESOLUTION OBSERVATIONS OF LASER EXCITED FLUORESCENCE IN $NO_{2}$ Hardwick, J. H. Fluorescence of nitrogen dioxide excited by several lines of an argon ion laser has been dispersed and recorded with a resolution of $0.05 cm^{-1}$. The fluorescence wavelengths thus observed allow precise vibrational and rotational constants to be determined for high-lying vibrational states of $NO_{2}$. The ``continuum'' fluorescence reported by previous workers exhibits no identifiable structure even at high resolution. $^{1}$S. Butler, C.Kahler, and D.H. Levy, J. Chem. Phys. 62, 815 (1975).

DIPOLE MOMENTS OF VIBRATIONALLY EXCITED FORMALDEHYDE

Dai, H. L. — 1982-01-01T00:00:00Z

DIPOLE MOMENTS OF VIBRATIONALLY EXCITED FORMALDEHYDE Dai, H. L.; Vaccaro, P. H.; Field, R. W.; Kinsey, J. L. Dipole moments for highly excited virbrational levels of formaldehyde in the $\tilde{\chi} {}^1{A}_{1}$ ground electronic state have been measured by utilizing the recently developed technique of Stimulated Emission Pumping (SEP) in conjunction with the Stark effect. Moments for the overtone and combination bands of the $\nu_{2}$ and $\nu_{4}$ vibrational modes are measured with better than 1% precision.

MICROWAVE SPECTRUM AND CONFORMATION OF CIS-1, 2-DIFLUOROETHYLENE OZONIDE (FCHOOFCHO)

Hillig, K. W., II — 1982-01-01T00:00:00Z

MICROWAVE SPECTRUM AND CONFORMATION OF CIS-1, 2-DIFLUOROETHYLENE OZONIDE (FCHOOFCHO) Hillig, K. W., II; Kuczkowski, R. L. The microwave spectrum of cis-difluoroethylene ozonide (cis-3, 5-difluoro-1, 2, 4-trioxolane) has been investigated by RF-microwave double resonance in the region of 26.5 - 40.0 GHz. The spectrum consists of two interwoven sets of transitions of similar intensity, arising from two vibrational states of the molecule. The predominant features of the DR spectra are several series of $\mu_{b}$ Q-branch pairs (pumped by $\mu_{c} RF$ transitions), with very few R-branch lines seen. The rotational constants of one state are A = 4256.9, B = 2923.7, and C = 2347.4, giving (A-C) = 1909.5 and k = -D.396. For the other state only Q-branch transitions have been assigned, giving (A-C)-1953.1 and $\kappa = -0.428$. The effects of centrifugal distortion are moderate, being < 150 MHz for the $J = 30 \leftarrow 30$ transitions. These results are consistent with a structure having axial fluorines, and with a ring conformation intermediate between a C-envelope and an $O_{ether}-C$ twist. Bond moment calculations suggest that $\mu_{c} > \mu_{b} > \mu_{a}$, in agreement with the observed spectrum. The presence of two states with intense spectra suggests that the first excited vibrational state is low compared with the $100-200 cm^{-1}$ range seen for other ozonides.

MICROWAVE SPECTRUM AND STRUCTURE OF 1,2,4-TRITHIOLANE (HCHSSHCHS)

Borseth, D. G. — 1982-01-01T00:00:00Z

MICROWAVE SPECTRUM AND STRUCTURE OF 1,2,4-TRITHIOLANE (HCHSSHCHS) Borseth, D. G.; Kuczkowski, R. L. The microwave spectrum of 1,2,4-trithiolane has been examined in the region 18.0 - 40.0 GHz. The spectrum consisted of A-dipole transitions which exhibited nuclear spin statistics (10:6) conforming to $C_{2}$ symmetry, similar to the analogous ethylene ozonide (1,2,4-trioxolane). The ground state rotational constants were determined to be 3819.37, 2621.11 and 1710.60 MHz. The dipole moment is $\mu_{t} = \mu_{a} = 0.47D$. 3,5-dideuterio-1,2,4-trithiolane has been prepared and all three possible species' microwave spectra have been assigned.

OZONOLYSIS OF CIS- AND TRANS-1,2-DIFLUOROETHYLENE: MICROWAVE SPECTRUM OF CIS, TRANS-1,2,3-TRIFLUOROCYCLOPROPANE

Agopovich, J. — 1982-01-01T00:00:00Z

OZONOLYSIS OF CIS- AND TRANS-1,2-DIFLUOROETHYLENE: MICROWAVE SPECTRUM OF CIS, TRANS-1,2,3-TRIFLUOROCYCLOPROPANE Agopovich, J.; Gillies, C. W. The microwave spectrum of cis, trans-1,2,3-trifluorocyclopropane, $CHFCHFCFH^{1}$, was investigated in the region of 26.5 = 40.0 GHz, From the assignment of $\mu_{a}$ and $\mu_{e}$ type R-branch transitions the following rotational constants (MHz) were obtained for the ground vibrational state: $A=4755,000 \pm 0.005, B=3145,729 \pm 0.002$ and $C = 2114.071 \pm 0.002$. The electric dipole moment was measured to be $\mu_{a} = 1.146 \pm 0.015$ Debye, $\mu_{c} =1.818 \pm .032$ Debye and $\mu_{T} = 2.149 \pm .035$ Debye. In addition, microwave transitions were assigned for a vibrationally excited state. Five deuterated isotopes of CHFCHFCFH were synthesized by the reaction of ozone with appropriately deuterated samples of 1,2-difluoroethylene, These include CHFCHFCFD, CHFCDFCFH, CDFCDFCFH, CDFCHFCFD, and CDFCDFCFD. The assignment of the microwave spectra of all five deuterated species has provided information related to the mechanism of cyclopropane formation in ozonolysis reactions. The results will be discussed in terms of carbene addition to the olefin. [FIGURE]

THE MICROWAVE SPECTRUM OF S-CIS AND S-TRANS ACROLEIN

Blom, C. E. — 1982-01-01T00:00:00Z

THE MICROWAVE SPECTRUM OF S-CIS AND S-TRANS ACROLEIN Blom, C. E.; Bauder, A. The microwave spectrum of the second conformer of acrolein has been assigned. Rotational constants A=22831.650 (16) MHz, B=6241.047 (3) MHz and C=4902.206 (3) MHz of s-cis acrolein in the vibrational ground states were determined from 42 transitions between 8 and 60 Ghz. The small value of the inertia defect establishes the planarity of the molecule. Rotational transitions in excited states of s-cis and s-trans acrolein have been analyzeed. The shifts of the rotational constants upon vibrational excitation have been interpreted on the basis of a flexible model for torsional motions and vibrational interactions.

MICROWAVE SPECTRA AND STRUCTURE OF METHYLGERMYL BROMIDE

Durig, J. R. — 1982-01-01T00:00:00Z

MICROWAVE SPECTRA AND STRUCTURE OF METHYLGERMYL BROMIDE Durig, J. R.; Mohamad, A. B.; Li, Y. S. The microwave spectra of ${CH_{3}}^{70}{GeH_{2}}^{70}Br, {CH_{3}}^{70}{GeH^{81}}Br, {CH_{3}}^{72}{GeH_{2}}^{79}Br, {CH_{3}}{GeH_{2}}^{81}Br, {CH_{3}}^{74}{GeH_{2}}^{79}Br$, and ${CH_{3}}^{74}{GeH_{2}}^{81}Br$ have been recorded from 18.0 to 39.0 GHz. Only a-type transitions were observed and R-branch assignments have been made for the ground vibrational state. From a diagnostic least-squares adjustment to fit the rotational constants, the $r_{0}$ structural parameters have been obtained. These results will be compared to the corresponding quantities in some similar molecules.

MICROWAVE TORSIONAL-ROTATIONAL SPECTRA OF $CH_{2}DSH$ AND $CHD_{2}SH^{\ast}$

Su, C. F. — 1982-01-01T00:00:00Z

MICROWAVE TORSIONAL-ROTATIONAL SPECTRA OF $CH_{2}DSH$ AND $CHD_{2}SH^{\ast}$ Su, C. F.; Quade, C. R. The torsional-rotational spectra of $CH_{2}DSH$ and $CHD_{2}SH$ have been studied from 12.4 to 50.0 GHz. For the symmetric (trans) configuration, rigid rotor n- and b-dipole transitions have been assigned. For the two asymmetric (gauche) configurations a-, b- and c-dipole lines have been assigned. In this case, the a-dipole lines show a small doubling and are nearly rigid rotor; the b-dipole lines have a large doubling due to internal angular momentum mixing the two asymmetric states and the second order contribution to the rotational coefficient A from the internal angular momentum; and the c-dipole lines are doubled to an even greater extent from the tunnelling between the even and odd states of the asymmetric configurations. Empirical spectroscopic constants will be presented along with the results of the internal rotation-rotation interaction based upon the molecular structure and the internal rotation potential energy. $^{\ast}$Supported by the Robert A, Welch Foundation.

R-BRANCH MICROWAVE SPECTRUM OF METHYLAMINE

Lees, R. M. — 1982-01-01T00:00:00Z

R-BRANCH MICROWAVE SPECTRUM OF METHYLAMINE Lees, R. M.; Malghani, M. S.; Mukhopadhyay, Indranath; McGhee, P.; Johnson, Donald R.; Lovas, F. J. The a-type R-branch $J=1 \leftarrow 0$ and $J = 2\leftarrow 1$ multiplets of $CH_{3}NH_{2}$ have been investigated at 44 GHz and 88 GHz, respectively, in order to provide laboratory data for radio astronomy and to permit determination of certain of the a-type molecular constants. Identification of all torsion- inversion components of the $J= 2 \leftarrow 1$ multiplet has been made for the ground torsional state, and partial identification for the first and second excited torsional states, Further progress has also been made on the assignment of the $J = 1 \leftarrow 0$ $multiplet^{1}$, and on the resolution of some ambiguities in the spectrum. The fitting of the spectra to a model employing semiempirical torsion-rotation distortion parameters will be discussed, and the preliminary molecular constants presented. $^{1}$K. Takagi and T. Kojima, J. Phys, Soc. Japan 30, 1145 (1971).

MICROWAVE SPECTRA OF DICHLORODIFLUOREMETHANE

Trannoy, P. — 1982-01-01T00:00:00Z

MICROWAVE SPECTRA OF DICHLORODIFLUOREMETHANE Trannoy, P.; Bellet, J. The microwave spectra of two isotopic species $C^{35}Cl2F2$ and $C^{35}Cl^{37} ClF2$ of dichlorodifluoremethane have been assigned. The spectra were all observed with a sample cell cooled at about $-70^{\circ}C$. and a conventional stark spectrometer or a video spectrometer using a superheterodyne detection. The hyperfine structure is analyzed. The rotational constants and the centrifugal distortion constants are determined by a least squares fit using the Watson's Hamiltonian.

OBSERVATIONS OF RABI OSCILLATIONS IN THE INFRA-RED ON THE Q(1, 1) TRANSITION OF METHLYL FLUORIDE

Adam, A. G. — 1982-01-01T00:00:00Z

OBSERVATIONS OF RABI OSCILLATIONS IN THE INFRA-RED ON THE Q(1, 1) TRANSITION OF METHLYL FLUORIDE Adam, A. G.; Gough, T. E.; Isenor, N. R.; Lewin, A.; Scoles, G. We shall report on the observation of Rabi oscillations for the $\Delta M = -1$, Q(1, 1) component of the $\upsilon_{3}$ band of methyl fluoride $(CH_{3}F)$ in the $10 \mu m$ spectral region. This coherence phenomenon has been observed in a beam produced by a supersonic expansion. The transition is detected by measuring, with a low temperature bolometer, the energy contents of the molecules in the beam downstream from the laser excitation region. A Stark field is used to shift the transition into resonance with a $CO_{2}$ laser line thereby circumventing the need for a tunable source. This work is preliminary to further observations of multiple excitation region coherence phenomena (e.g. Ramsey fringes) and their perturbation by molecular collisions.

THE GEOMETRY AND MOLECULAR PROPERTIES OF THE ETHYLENE-HCN AND ACETYLENE-HCN DIMERS

Aldrich, P. D. — 1982-01-01T00:00:00Z

THE GEOMETRY AND MOLECULAR PROPERTIES OF THE ETHYLENE-HCN AND ACETYLENE-HCN DIMERS Aldrich, P. D.; Read, W. G.; Kukolich, Stephen G.; Campbell, E. J. The microwave spectra of the acetylene-HCN and ethylene-HCN dimers has been observed in the 4-18 GHz region using the pulsed Fourier transform method where the gas mixture is pulsed into a Fahry-Perot cavity. The spectra reveal both dimers to be near prolate asymmetric tops (K = -.99) in their ground vibrational states. Both dimers have a `T' shape for an equilibrium structure with the proton of HCN nearest to acetylene or ethylene. The ethylene-HCN dimer is nonplanar. Hyperfine structure originating from interaction of the nuclear electric quadrupole moment of $^{14}N$ with the surrounding electric field gradient is evident in all transitions. The nucleum quadrupole coupling analysis shows $X_{bb}$ and $X_{cc}$ to be equal within experimental uncertainty in both cases indicating that the proton of HCN experiences a nearly isotropic potential due to ethylene or acetylene. The structure of both dimers is consistent with other acetylene (ethylene)-HX dimers studied in this laboratory in structure and approximate well depth.

MEASUREMENTS OF HYPERFINE STRUCTURE IN $NONO_{2}$ AND $PH_{2}$D USING THE FLYGARE-BALLE PULSED BEAM SPECTROMETER

Kukolich, Stephen G. — 1982-01-01T00:00:00Z

MEASUREMENTS OF HYPERFINE STRUCTURE IN $NONO_{2}$ AND $PH_{2}$D USING THE FLYGARE-BALLE PULSED BEAM SPECTROMETER Kukolich, Stephen G. The Fourier transform - pulsed beam microwave $spectrometer^{1, 2}$ developed by W.H. Flygare, T.J. Balle and coworkers allows high resolution measurements of rotational transitions on molecules which are difficult or impossible to measure using standard techniques. Previous measurements have been made on both $NONO_{2}$ and $PH_{2}D$, but at much lower resolution. Far $NONO_{2}$ hyperfine structure due to both nitrogen atoms was completely resolved and quadrupole coupling tensors were obtained. The values obtained differ significantly from those obtained for the free molecules NO and $NO_{2}$. Splitting of the rotational transitions in $PH_{2}D$ was observed due to the $^{31}P$ spin-rotation interaction and $^{1}H$ spin-rotation interaction. Deuterium quadrupole coupling and inversion splitting were not resolved. The upper limit on the Inversion splitting from these measurements is 20 KHz. $^{1}$T.J. Balle, E.J. Camphell, M.R. Keenan and W.H. Flygare, J. Chem. Phys. 71, 2723 (1979); 72, 922 (1980) $^{2}$T.J. Balle and W.H. Flygare, Rev. Sci. instrum. 52, 33 (1981)

THE MICROWAVE SPECTRUM OF THE BENZENE-HCl HYDROGEN BOND COMPLEX

Read, W. G. — 1982-01-01T00:00:00Z

THE MICROWAVE SPECTRUM OF THE BENZENE-HCl HYDROGEN BOND COMPLEX Read, W. G.; Campbell, E. J.; Henderson, G. The microwave spectrum of benzene-HCl was studied in the gas phase using a pulsed Fourier-transform microwave spectrometer employing a Fabry Perot Cavity and a pulser supersonic nozzle as the molecular source. The $1 \rightarrow 2, 2 \rightarrow 3, 3 \rightarrow 4$ and $4 \rightarrow 5$ R branches were observed for benzene $H^{35}Cl$ and $D^{35}Cl$. The $3\rightarrow 4$ and $4 \rightarrow 5$ R branches were observed for benzene $H^{37}Cl$ and benzene $D^{37}Cl$. The microwave spectrum was characteristic of a symmetric top with the time averaged displacement of the H and Cl atoms from the $C_{6}$ axis being zero. Deuterium substitution of HCl demonstrated that the acidic proton lies between Cl and the benzene ring. $\chi^{Cl}_{aa}$ was measured for all four isotopes and is interpreted in terms of vibrationally averaging $\chi^{Cl}_{o}$ in HCl over two degenerate bending modes involving the angle between the $C_{6}$ axis and the HCl bond. The microwave spectrum, structure and interpretation of spectroscopic constants will be discussed.

HYPERFINE STRUCTURE IN MICROWAVE TRANSIENT SPECTROSCOPY

Coy, Stephen L. — 1982-01-01T00:00:00Z

HYPERFINE STRUCTURE IN MICROWAVE TRANSIENT SPECTROSCOPY Coy, Stephen L.; Fraser, J. Corrections for magnetic hyperfine splittings are necessary in measurement of rotational relaxation rates and of the speed-dependence of rotational relaxation rates from transient emission measurements. For some systems, transient spectroscopy shows promise for measurement of hyperfine splittings and intensities. Results are presented for $H_{2}O, H_{2}CO, ^{15}N_{2}O$, and $\C_{2}H_{4}O$.

SELF-CONSISTENT ANALYSIS FOR LINE POSITIONS OF CARBON DIOXIDE

Rothman, Laurence S. — 1982-01-01T00:00:00Z

SELF-CONSISTENT ANALYSIS FOR LINE POSITIONS OF CARBON DIOXIDE Rothman, Laurence S.; Esplin, Mark P. A high resolution Fourier transform spectrometer coupled with a high temperature (800k) absorption cell have produced spectra for carbon dioxide in the $1600 to 2500 cm^{-1}$ $region^{1}$. These new data provide access to very high rotational levels. The measurements have been combined with the best available high resolution observations in other regions of the infrared and a procedure has been implemented to provide a global set of constants. The self-consistent set of energy levels and rotational constants that are derived have been used ot predict the positions of $CO_{2}$ IR transitions of significance to problems of atmospheric option. $^{1}$M.P. Esplin, R.J. Huppi, H. Sakai, G.A. Vanasse, and L.S. Rothman, ``Absorption Measurements of $CO_{2}$ and $H_{2}O$ at High Resolution and Elevated Temperatures,'' AFGL-TR-0057 (1982). This work was supported by the Air Force Office of Scientific Research.

WHOLE BAND ANALYSIS OF ABSORPTION BANDS OF CARBON DIOXIDE IN THE SPECTRAL RECION $3.6 TO 4.0 \mu m$.

Hoke, M. — 1982-01-01T00:00:00Z

WHOLE BAND ANALYSIS OF ABSORPTION BANDS OF CARBON DIOXIDE IN THE SPECTRAL RECION $3.6 TO 4.0 \mu m$. Hoke, M.; Shaw, J. H. The technique of whole band $analysis^{1}$ has been used to obtain, simultaneously, line parameter estimates from three band $systems^{2}$ between $3.6 and 4.0 \mu m$. These systems include two Fermi resonant triads of the transition (2000-0000) of the isotopes ${^{16}o}{^{12}c}{^{10}O}$ and ${^{16}o}{^{12}c}{^{17}o}$. Parameter estimates, including rotational band constants, collision half-widths and band strengths are presented. In addition, modification of the spectra and their affect on the parameter estimates, produced by instrumental effects, are discussed. This work was supported by National Aeronautics and Space Administration grant No. NSC-7479. $^{1}$C. L. Lin, J.H. Shaw, and J.G. Calvert, JQSRT, 23, 387 (1980). $^{2}$M.L. Hoke, J.H. Shaw, Applied Optics,, in press.

FTS BAND INTENSITY MEASUREMENTS ON OCS AND $N_{2}O$

Kagann, Robert H. — 1982-01-01T00:00:00Z

FTS BAND INTENSITY MEASUREMENTS ON OCS AND $N_{2}O$ Kagann, Robert H. The infrared intensities of nine absorption bands of OCS and thirteen absorption bands of $N_{2}O$ have been measured with a Fourier transform spectrometer at $0.06 cm^{-1}$ resolution. The measured bands lie between $500 cm^{-1}$ and $4600 cm^{-1}$, and include all fundamentals of each molecule and also overtone and combination bands. All measurements were made at room temperature. The partial pressure of the absorbing species ranged from 0.76 torr to 38 torr and the absorption pathlengths ranged from 1 to 15 cm resulting in pressure-pathlength products of 0.78 torr cm to 567 torr cm. The stronger bands were measured at the lower pressure-pathlengths and the weaker bands at the higher pressure-pathlengths. In all runs the absorption call was pressurized to 1 atm. with nitrogen to ensure minimal instrumental distortion of the spactral features. Care was also taken to observe any saturation of the absorption bands (which generally occur at peak absorptions greater than 40%) and omit any saturation distorted data. The band strengths were obtained directly from the slopes of Bear's law plots-integrated absorbance versus pressure-pathlength product $(\int-\ln (I/I_{0}) d\nu va P.L)$.

WHOLE-BAND ANALYSIS OF THE $\nu_{1}+2\nu_{2}$ BAND OF $N_{2}O$ BROADENED BY NITROGEN, OXYGEN AND $AIR^{\ast}$

Hawkins, R. L. — 1982-01-01T00:00:00Z

WHOLE-BAND ANALYSIS OF THE $\nu_{1}+2\nu_{2}$ BAND OF $N_{2}O$ BROADENED BY NITROGEN, OXYGEN AND $AIR^{\ast}$ Hawkins, R. L.; Shaw, J. H. Foreign-broadened line widths, and the rotational dependence of line intensities, in the $\nu_{1}+2\nu_{2}$ vibration-rotation band of $N_{2}O$ have been determined by nonlinear least-squares, whole band analysis. The retrieved nitrogen-broadened widths agree with the revised values reported by $Toch.^1$ The retrieved nitrogen-, air- and oxygen-broadened widths indicate that the air-broadened widths in the AFGL line listing should be reduced by approximately 10%. The rotational dependence f(m) =(M = -J"" in the P-branch, =J"" + 1 in the R-branch) of the line intensities was modelled by: $f(m) = 1+\beta_{1} m + \beta_{2} m^{2}, \beta_{1}$ and $\beta_{2}$ were retrieved, with the largest $|m|$ in the spectrum of approximately 40. Analysis of several spectra showed that $\beta_{1}$ is not significantly different from zero, $\beta_{1} = 0.5 (\pm 3.0) \times 10^{-4}$, while $\beta_{2}$ is $0.645(\pm 0.006) \times 10^{-4}$. $^{\ast}$ This work was supported in part by NASA Grant NSG 7479. 1. R.A. Toth, paper TE4, 36th Annual Symposium on Molecular Spectroscopy (1981).

CALCULATION OF INFRARED INTENSITIES FOR THE FUNDAMENTAL VIBRATIONS OF $HCO^{+}$ AND $HOC^{+}$

Rogers, J. D. — 1982-01-01T00:00:00Z

CALCULATION OF INFRARED INTENSITIES FOR THE FUNDAMENTAL VIBRATIONS OF $HCO^{+}$ AND $HOC^{+}$ Rogers, J. D.; Hillman, J. J. Absolute infrared intensities and dipole moment drivatives expressed in atomic polar tensor from are calculated quantum machanically using the 4-31G and $6-31G^{\ast\ast}$ basic sets for the $HCO^{+}$ species and for the isomeric $HOC^{+}$ form, The infrared intensities predicted for these ions are compared with the infrared intensities of other molecules containing carbonyl groups or hydroxyl groups, and the fundamental vibrations of the $HOC^{+}$ ion are found to be quite strong. Charge, charge flux, and overlap contributions to the dipole moment derivatives calculated for the ions show interesting similarities to those for the other isoelectronic species HCN, HNC, and CO.

CARBON DIOXIDE ON TITAN

Maguire, W. C. — 1982-01-01T00:00:00Z

CARBON DIOXIDE ON TITAN Maguire, W. C.; Hanel, R.; Jennings, D.; Kunde, V. G.; Samuelson, R.; Aikin, A.; Yung, Y. The infrared spectra returned by Voyager 1 of the atmosphere of Titan Saturn's largest moon, have shown the presence of eleven gaseous molecular $species.^{1 2 3}$ All of these previously reported species are compounds of hydrogen, carbon, and nitrogen. We have now identified a feature in the Titan spectra at $657 cm^{-1}$ as being due to the $\nu_{2}$ Q-branch of carbon dioxide. The identification of $CO_{2}$ is based on frequency correspondence between observed spectra and laboratory measurements, and on the elimination of alternative species which might be present in Titan's atmosphere. A mole fraction of $7\times 10^{-10}$ has been determined for $CO_{2}$ from the $667 cm^{-1}$ feature. $^{1}$R. Hanel. et. al., Science 212, 192 (1981). $^{2}$W.C. Maguire, et. al., Nature 292, 683 (1981). $^{3}$V.G. Kunde, et. al., Nature 292, 686 (1981).

LINE STRENGTH MEASUREMENTS OF NO IN THE $5\mu m$ REGION

Atakan, A. K. — 1982-01-01T00:00:00Z

LINE STRENGTH MEASUREMENTS OF NO IN THE $5\mu m$ REGION Atakan, A. K.; Halsey, G. W.; Blass, W. E.; Dakhil, M. A.; Gailar, Norman M.; Daunt, S. J. Line strengths have been determined for a number of P and R branch lines of the 1-0 band of NO. Data was obtained using the 5-meter Littrow spectrometer operating under computer control, The reproducibility of successive scans of a line with the stepping motor driven tangent arm-system permits averaging of a number of successive scans of each line to improve the precision of the results. Because the A-doubling is not fully resolved, explicit treatment of the A- doubling in the equivalent width calculations is necessary. Details of the calculations as well as $NO_{1}$ line strengths are presented. Results will be compared with recently published $strengths.^{1}$ $^{1}$J.-Y. Mandin, C, Amiot., G, Guelachvili, Amm, Phys, Fr., 5, 91-112 (1980).

PURE ROTATIONAL RAMAN LINE WIDTHS OF $O_{2}$

Fletcher, W. H. — 1982-01-01T00:00:00Z

PURE ROTATIONAL RAMAN LINE WIDTHS OF $O_{2}$ Fletcher, W. H.; Atakan, A. K.; Halsey, G. W.; Blass, W. E. The pure rotational Raman lines of oxygen have been observed at a resolution of $0.06 cm^{-1}$ in order to determine the line widths for spontaneous scattering. The $S_{0} (J)$ lines from J-1 to 19 were recorded with an argon laser operating in single mode, using the $4880, 5145, 4765 and 4965\AA$ lines for excitation. Data were acquired in the pressure range of one half to two atmospheres. Numerous scans of each line were averaged and fitted to Voigt profiles to determine the collision widths of the observed Stokes lines. The results are presented and compared with simulations based on calculated fine structure for each line.

ON THE DETERMINATION OF VIBRATIONAL RAMAN SCATTERING CROSS SECTIONS AND POLARIZABILITY MATRIX ELEMENTS: PARTIALLY FLUORINATED METHANES

Murphy, W. F. — 1982-01-01T00:00:00Z

ON THE DETERMINATION OF VIBRATIONAL RAMAN SCATTERING CROSS SECTIONS AND POLARIZABILITY MATRIX ELEMENTS: PARTIALLY FLUORINATED METHANES Murphy, W. F. The measurement of the spectral data needed to determine scattering cross sections for vibrational Raman transitions in gas phase molecules can usually be accomplished without great difficulty using currently available techniques. However, it is often necessary to separate contributions from two or more vibrational modes whose bands overlap, or to separate the contributions to a single mode by two or more polarizability matrix elements. This problem occurs in the evaluation of the polarizability matrix elements of the partially fluorinated methanes: methyl fluoride, methylene fluoride and fluoroform, and various approaches may be taken to solve it. Intensity data for several isotopically substituted species can be analyzed simultaneously to find such contributions. Relative values of polarizability matrix elements can be obtained in an analysis of high resolution vibration-rotation spectra of overlapping or degenerate bands. Recent results from ab initio Raman intensity calculations reproduce observed values with acceptable accuracy; such results, if available, may provide guidance in separating contributions from different polarizability matrix elements. In the present instance, an attempt is being made to estimate the contributions of the different polarizability matrix elements to the scattering cross sections of the partially fluorinated methanes using a bond polarizability model. Initial attempts to exploit the transferability of bond parameters between these related molecules have been disappointing. The current status of this investigation will be presented.

INTENSITIES OF HALOCARBON F-11 AND F-12 BY INFRARED FOURIER TRANSFORM SPECTROSCOPY IN THE 8-16 MICRON REGION

Kagann, Robert H. — 1982-01-01T00:00:00Z

INTENSITIES OF HALOCARBON F-11 AND F-12 BY INFRARED FOURIER TRANSFORM SPECTROSCOPY IN THE 8-16 MICRON REGION Kagann, Robert H.; Sams, Robert L.; Elkins, J. W. Four of the strongest bands in Halocarbon F-12, $CCl_{2}F_{2}$ and three of the strongest bands in Halocarbon F-11, $CCl_{3}F$, have been measured with a moderate resolution $(0.06 cm^{-1})$ Fourier transform spectrometer. Care was taken to make sure that the Halocarbons were not being absorbed in the cell or in the transfer manifold by removing all elastomers. The samples were pressure broadened with nitrogen to one atmosphere. Most of the bands are in general agreement with other published results except $\nu_{4}$ of halocarbon F-11 at $846 cm^{-1}$. The present work indicates that the intensity of this band is $1828 \pm 12 cm^{-2} atm^{-1}$ about 15% higher than $Varanasi and Ko^{1}$ and 6% higher than $Goldman et al^{2}$. $^{1}$P. Varanasi and F-k Ko, J. Quant. Spectrosc. Radiat. Transf. 17, 385-8 (1977). $^{2}$A. Goldman. F.S. Bonomo, and D.G. Murcray, Appl. Opt. 15, 2305-7 (1976).

DIODE LASER MEASUREMENTS OF LINE STRENGTHS IN THE $\nu^{2}$ BAND OF $H_{2}S$

Strow, L. — 1982-01-01T00:00:00Z

DIODE LASER MEASUREMENTS OF LINE STRENGTHS IN THE $\nu^{2}$ BAND OF $H_{2}S$ Strow, L. The $\nu_{2}$ band of $H_{2}S$ exhibits remarkably large intensity perturbations due to centrifugal distortion. A previous low resolution study of this $band^{1}$ found that the P branch is about 1/5 as intense as the R branch. In this work, the strengths of 94 lines in the $\nu_{2}$ band have been measured to an average accuracy of 3% using a tunable diode laser. Since the observed low pressure line widths are on the average only 1.3% larger than the calculated Poppler widths, the line profile distortion is small, and thus the strengths could be determined using the line center absorption with slight corrections to account for residual line broadening by the laser bandwidth and gas pressure. The maximum values of J, $K_{a}$, and $K_{e}$ observed are 12, 7, and 10 respectively. The measured line strengths range from 5 times larger to 17 times smaller than strengths calculated using a Watson-type Hamiltonian with an untransformed dipole moment operator. 1. M.T. Emerson and D.F. Eggers, J. Chem. Phys, 37, 251 (1962).

ANALYSIS OF HIGH TEMPERATURE SPECTRA OF ${^{12}C}{^{16}O}{^{18}O}$ and ${^{12}C}{^{18}O_{2}}$ IN THE $4.3 \mu m$ REGION

Esplin, Mark P. — 1982-01-01T00:00:00Z

ANALYSIS OF HIGH TEMPERATURE SPECTRA OF ${^{12}C}{^{16}O}{^{18}O}$ and ${^{12}C}{^{18}O_{2}}$ IN THE $4.3 \mu m$ REGION Esplin, Mark P.; Rothman, Laurence S.; Vanasse, G. A.; Huppi, R. J. High resolution $(0.007 cm^{-1})$ absorption spectra of isotopically enriched $CO_{2}$ at 800K have been obtained using the Air Force Geophysics Laboratory (AFGL) high resolution interferometer. The enriched sample provided by the Los Alamos National Laboratory contains 46% ${^{12}C}{^{16}O}{^{18}O}$ and 17% ${^{12}C}{^{18}O_{2}}$. Measurements were made with a gas pressure of 3 and 6 Torr using a 3.5 meter high temperature absorption cell. In addition to spectra taken at 800K, observations were also made at 500K and 300K to assist in the identification of the densely packed spectra, Improved spectroscopic constants which predict the positions of lines belonging to the vibration-rotation bands which have been identified, will be presented. This work was supported by the Air Force Office of Scientific Research.

HIGH RESOLUTION STIMULATED RAMAN SPECTROSCOPY OF $0_{2}^{\ast}$

Hill, R. A. — 1982-01-01T00:00:00Z

HIGH RESOLUTION STIMULATED RAMAN SPECTROSCOPY OF $0_{2}^{\ast}$ Hill, R. A.; Esherick, P.; Owyoung, A. High resolution $(0.002 cm^{-1})$ stimulated Raman $spectra^{1}$ of the fundamental vibrational band of $0_{2}$ have been recorded at room temperature and, using a pulsed free-expansion $jet^{2}$, at 50k. These spectra include the normal Q-branch and the satellite Q-branches at $1554 cm^{-1}$ and $1558 cm^{-1}$ that arise due to the splitting of the $^{3}\Sigma_{g}$ ground state of molecular oxygen by spin-spin and spin-rotation interactions. Both satellite Q-branches were completely resolved for the first time. Measured intensity ratios for the ${\Delta N}\Delta J(J.N) = ^{Q} 0(2,1)$ and $^{Q} R(1,1)$ lines, and for the $^{Q} S(0,1)$ and $^{Q} P(2,1)$ lines compare favorably with that for a coupling case intermediate between Hund's Cases (a) and (b). Depolarization ratios, measured for a series of $Q^{Q}$-branch (unresolved) triplets. give a value $0.164 \pm 0.004$ for the depolarization ratio of the fundamental vibrational band. $^{1}$A. Owyoung in Laser Spectroscopy IV (H. Walther and K.W. Rothe, ed.) Springer-Verlag, Berlin, 1979, p.175. $^{2}$J.J. Valentini, P.Esherick and A. Owyoung. Chem. Phys. Lett. 75, 590 (1980). $^{\ast}$ This work is supported by the U.S. Department of Energy

AN ANALYSIS OF THE ROTATIONAL STRUCTURE IN THE $C^{1}\pi - X ^{1}\Sigma^{+}$ SYSTEM OF GAF

Griffith, W. B. — 1982-01-01T00:00:00Z

AN ANALYSIS OF THE ROTATIONAL STRUCTURE IN THE $C^{1}\pi - X ^{1}\Sigma^{+}$ SYSTEM OF GAF Griffith, W. B.; Bickel, G. A.; Mathews, C. W. The emission and absorption spectra of CaF have been examined by $Barrow and co-workers.^{1,2}$ Their studies, as well as studies of the microwave $spectrum^{3}$, show that the ground state is $X ^{1}\Sigma^{+}$. There is a $^{3}\pi - ^{1}\Sigma^{+}$ transition near $3000 \AA$ and a $^{1}\pi - ^{1}\Sigma^{+}$ transition near $2100 \AA$. The present paper deals with the rotational analysis of this $C ^{1}\pi - X ^{1}\Sigma^{+}$ system. Barrow et al obtained estimates of the upper state rotational constants from measurements of the P and Q or Q and R head separations in this system. The existence of the Q heads and the presence of $^{69}Ga$ and $^{71}Ga$ in a natural abundance of 3:2 also permitted a very good vibrational analysis of the system. Our present study of the absorption spectrum yielded resolved rotational structure for the (0-0) band. The rotational constants of the $X^{1}\Sigma^{+}$ state were initially fixed at the values obtained by microwave $studies.^{2}$ The resolved P and R branches were then fitted to yield constants (in $cm^{-1}$) for $v = 0$ of the $C^{1}\Pi$ state of $\nu_{00} = 47 323,24$, $B = 0.3579$, and $D = 7.3 \times 10^{-6}$. Our inability to resolve the Q branch prevented us from obtaining any information regarding lambda-type doubling in the upper state. Efforts are currently being made to obtain the spectrum at somewhat higher resolution and extend the rotational analysis to other bands. $^{1}$ D. Welti. R.F. Barrow, Proc, Phys, Soc, A 65, 629 (1952) $^{2}$R.F. Barrow, J.A.T. Jacquest, E.W. Thompon. Proc. Phys. Sec. A 67, 528 (1954) $^{3}$J. Hoeft, F.J. Lovas, E. Tieman, T. Torring, 2, Naturforsch. 25a 1029 (1970)

PERIODIC SYSTEM OF DIATOMIC AND n-ATOMIC MOLECULES: STATUS REPORT

Hefferlin, R. — 1982-01-01T00:00:00Z

PERIODIC SYSTEM OF DIATOMIC AND n-ATOMIC MOLECULES: STATUS REPORT Hefferlin, R. We analysed tabulated data for neutral and ionized diatomic molecules: thermodynamic properties, ionicity, condensation point, 16 spectroscopic/collision properties and for 6 of them $(\Delta prop,/\Delta ioniz.) \theta constant n_{C}$ and for 4 of these (d prop./d ioniz.) $\theta constant n_{C}.^{1}$ These data firstly support a periodic system of diatomic molecules (PSDM) which initially assumes the two atoms to have weak $interaction.^{2}$ The PSDM is constructed in 4-space by direct product of the periodic chart of the atoms (PCA), a matrix, with $itself.^{3}$ Visualizable 3-d projections will be shown. This construction suggests that properties common to atoms and to molecules should be multiplicative or additive. Some properties are, e.g. number of electrons (!), radit and $r_{e}$ (poorly), and (d IP/d ioniz.) $\theta constant n_{e},^{4}$ The data secondly support refinements of the PSDM based on group theory, which turn rests on a preferred form of the $PCA.^{5}$ Diatomics have been classified according to isoelectronic series and to extent of heteronuclearicity by means of operators compatible with the group. The construction based on the direct product, and the transformation to isoelectronic and heteronuclear coordinates, are being generalized to n-atomic molecules. An algorithm exists for mapping ionized diatomic molecules onto the coordinate frame of the PSDM. Least-squares fitting of data for neutral (with, if desired, ionized) molecules to simple functions of from one to four coordinates has begun and some $r_{e}$ have $predicted.^{2}$ $^{1}$ R. Hefferlin and M. Kutzner, J. Chem. Phys. 75, 1035 (9181): C.H. Cillespie and M. Inokuti, Phys. Rev. A, 22, 2430 (1980); more in bibliography for reference #4. $^{2}$ R. Hefferlin et al, J. Quant. Spectr. Rad. Transfer 21, 315 and 337 (1979). $^{3}$ R. Hefferlin and H. Kuhlmean, J. Quant. Spectr. Rad. Transfer 24, 379 (1980). $^{4}$ R. Hefferlin and W. Innis, submitted to J. Chem. Phys. $^{5}$ G. V. Jhuvikin and R. Hefferlin, Khimicheskaya Phyaika (new Soviet journal), in press; Report SMC #2400ay for National Academy of Sciences, appendix, September 17, 1981.

DIATOMIC THERMODYNAMIC FUNCTIONS AT HIGH TEMPERATURE

Julienne, P. S. — 1982-01-01T00:00:00Z

DIATOMIC THERMODYNAMIC FUNCTIONS AT HIGH TEMPERATURE Julienne, P. S.; Mies, F. H. Partition functions of diatomic molecules at low temperature are normally calculated from spectroscopic data for the low lying bound states. At high temperature, however, questions arise concerning how to treat the unbound molecular states, i.e., the quasibound resonances and the continuum vibrational states. A quantum formulation of the diatomic partition function is developed which uses the energy variation of the elastic scattering phase shift to represent the phase space associated with the molecular continuum states. The resonance structure in the phase shift due to tunnelling through rotational barriers, gives a rigorous interpretation of the metastable states which lie behind the barrier, and we can justify the need to include such states in evaluation of thermodynamic properties. However, it is inconsistent to merely include the metastable phase without considering the remaining contributions from the continuum. We will show the correspondence between the exact quantal results and the approximation classical expressions for high temperature. The classical theory gives a simple and accurate procedure for extending thermodynamic tables to elevated temperature. Explicit calculations are presented for $Li_{2}$ and $Na_{2}$ and compared to the usual spectroscopic analysis inherent in the JANAF tables. Significant discrepancies occur for temperatures above $3000^\circ K$.

A THEORETICAL INVESTIGATION OF THE ORIGINS OF THE GREEN AND RED SPECTRA OF $Ca_{2}$

Rosenkrantz, Marcy E. — 1982-01-01T00:00:00Z

A THEORETICAL INVESTIGATION OF THE ORIGINS OF THE GREEN AND RED SPECTRA OF $Ca_{2}$ Rosenkrantz, Marcy E.; Krauss, M.; Stevens, W. J. The assignments of the emission spectra of $Ca_{2}$ in the red and in the green has been the subject of discussion recently at this Symposium (1) and in the literature (2,3). A definitive set of assignments has not yet been agreed upon. We have calculated the potential energy curves and transition moments of the ground $^{1}{\Sigma^{+}_{g}}$ and $1,2 {^{1}{\Sigma^{1}}_{u}}$ states of $Ca_{2}$ using a first order CI approach. These calculations support the assignment of the observed red and green emission spectra of $Ca_{2}$ to transitions between the ground state and the $1,2 {^{1}{\Sigma^{+}}_{u}}$ states, respectively. Prediassociation of the $1 {^{1}{\Sigma^{+}}_{u}}$ state by the $1 {^{3}\pi_{u}}$ state is shown the be possible. 1. J.C. Wyaa, paper RE13 34th Symposium on Molecular Spectroscopy, Columbus, Ohio (June 1979). 2. W.J. Balfour and R.F. Whitlock, Can. J. Phys. 53, 472 (1975). 3. J.C. Miller and L. Andrews, Appl. Spectrose. Rev. 16, 1 (1980), and references therein.

RYDBREG STATES OF ${Li_{2}}$ AND MOLECULAR CONSTANTS OF ${Li_{2}}^{+}$

Bernheim, R. A. — 1982-01-01T00:00:00Z

RYDBREG STATES OF ${Li_{2}}$ AND MOLECULAR CONSTANTS OF ${Li_{2}}^{+}$ Bernheim, R. A.; Gold, L. P.; Tipton, T. Thirty-one new excited gerade states of $^{7}Li_{2}$ have been characterized by means of pulsed optical-optical double resonance spectroscopy. Twenty-nine of these have been identified as the lowest members of three Rydberg series: $3-15d\pi^{1}\Pi_{g}, 3-10d\sigma^{1}{\Sigma^{+}}_{g}$, and $3-10s\sigma^{1}{\Sigma_{g}}^{+}$, A fit of a Rydberg formula to the $^{1}{\Pi^{-}}_{g}$ term energies yield a value of $41496\pm 4 cm^{-1}$ for the ionization potential of $Li_{2}$. Extrapolations of the vibrational frequencies, rotational constants, and dissociation energies of these states give estimates for the corresponding quantities for the ground state of ${Li_{2}}^{+}$ which are in good agreement with those obtained by ab initio $calculations^{1}$. $^{1}$ D.D. Konowalow and M.E. Rosenkrantz, Chem. Phys. Letters 61, 489 (1979).

AN OVERVIEW OF THE STRUCTURE AND SPECTRA OF THE 26 LOWEST-LYING STATES OF $Li_{2}$

Konowalow, Daniel D. — 1982-01-01T00:00:00Z

AN OVERVIEW OF THE STRUCTURE AND SPECTRA OF THE 26 LOWEST-LYING STATES OF $Li_{2}$ Konowalow, Daniel D.; Fish, J. L. Ab initio configuration-interaction computations which invoke an effective core potential approximation are used to describe the 26 lowest-lying states of $Li_{2}$. The quality of the computations are assessed by an analysis of the asymptotic long-range behavior of the potentials and by a comparison of the computed vibrational energy levels with those deduced from spectra. Typical asymptotic results are: $C_{6} = 1430 (1400) e^{2}{a_{0}}^{5}$ for the $1 ^{1}{\Sigma^{+}}_{g}$ and $1^{3}{\Sigma^{+}}_{u}$ states: $C_{3} = 11.14 (11.04) e^{2}{a_{0}}^{2}$ for the $2^{1}{\Sigma^{+}}_{g}$ and $2^{3}{\Sigma^{+}}_{u}$ states. (Literature values are in parenthesis). Scaling the calculated $1^{1}{\Sigma^{+}}_{g}$ potential curve against observed vibrational energy spacings gives a dissociation energy $D_{e} = 8490 (8450,8505) cm^{-1}$. We make special mention of ion-pair effects on the structure and spectra of a number of states.

THE ELECTRONIC TRANSITION DIPOLE MOMENT FUNCTIONS FOR TRANSITIONS AMONG LOW-LYING STATES OF $Li_{2}$ AND $Na_{2}$

Konowalow, Daniel D. — 1982-01-01T00:00:00Z

THE ELECTRONIC TRANSITION DIPOLE MOMENT FUNCTIONS FOR TRANSITIONS AMONG LOW-LYING STATES OF $Li_{2}$ AND $Na_{2}$ Konowalow, Daniel D.; Rosenkrantz, Marcy E.; Hochhauser, D. The electronic transition dipole moment functions are computed ab initio for transitions among low-lying states of $Li_{2}$ and $Na_{2}$.

BOUND-BOUND AND BOUND-FREE FLUORESCENCE FROM THE $A^{1}\Sigma^{+}$ STATE TO THE $X^{1}\Sigma^{+}$ STATE IN LIH

Zemke, W. T. — 1982-01-01T00:00:00Z

BOUND-BOUND AND BOUND-FREE FLUORESCENCE FROM THE $A^{1}\Sigma^{+}$ STATE TO THE $X^{1}\Sigma^{+}$ STATE IN LIH Zemke, W. T.; Sando, K. M.; Verma, K. K.; Harding, D. R.; Stwalley, W. C. Using experimentally-based potential energy $curves^{1}$ and a theoretical transition $moment^{2}$, we report calculated bound-bound and bound-continuum radiative transition probabilities for several high-lying v' levels of the $A^{1}\Sigma^{+}$ state in LiH, We will interpret the broad oscillatory structures in the continuum region as well as the region of the threshold between the bound and continuum levels of the X state. Our calculations include proper, non-zero rotational dependence. We have recently observed fluorescence from $^{6}LiH, ^{7}LiH$ and $^{7}LiD$ excited by UV lines of an argon ion laser (3336, 3345 and $3358 \AA$, respectively). The levels excited in the $A^{1}\Sigma^{+}$ state for these three cases are (v', J') = (12, 10), (16, 9) and (19, 22), respectively, so significant bound-free emission is expected in addition to the bound-bound emission already observed. In the case of emission from the $A^{1}\Sigma^{+} (v'=26, J'=0)$ long-range level to the $X^{1}\Sigma^{+} (k"", J""=1)$ levels, a very strong enhancement in the intensity occurs right at the threshold transition energy. This very narrow and extremely intense line is interpreted as due to existence of a quasibound level in line X state when J""=1. $^{1}$ W.C. Stwalley, W.T. Zemke, K.R. Way, K.C. Li and T.R. Proctor, J. Chem. Phys. 66, 5412 (1977); erratum 67, 4785 (1977). $^{2}$ K.K. Docken and J. Hinze, J. Chem. Phys. 57, 4936 (1972).

THE DISSOCIATION ENERGY OF $CS_{2}$

Raab, M. — 1982-01-01T00:00:00Z

THE DISSOCIATION ENERGY OF $CS_{2}$ Raab, M.; Weickenmeier, H. By means of high resolution laser polarization spectroscopy of the C-X $system^{1}$ a new excited state in the cesium dimer, the `D' - state was observed. Dye laser excitation within this $D^{1}{\Sigma^{+}}_{u}\leftarrow X^{1}{\Sigma^{+}}_{g}$ system yields extended fluorescence progressions ranging from $\nu""=0$ up to $\nu"" = 140$. The analysis of the fluorescence spectra and the application of the Leroy-Bernstein method to the determination of the dissociation limit results in a dissociation energy of $D_{e} = 3648 \pm 5 cm^{-1}$, which is two orders of magnitude more accurate than previously known. $^{1}$M. Raab, G. Honing, W. Demtroder, and C.R. Vidal, J. Chem. Phys., (1982) in press

LASER-EXCITED FLUORESCENCE OF $I_{2}$: VARIATION OF ELECTRONIC TRANSITION MOMENT IN THE B-X SYSTEM

Bhale, G. L. — 1982-01-01T00:00:00Z

LASER-EXCITED FLUORESCENCE OF $I_{2}$: VARIATION OF ELECTRONIC TRANSITION MOMENT IN THE B-X SYSTEM Bhale, G. L.; Ahmad, S. F.; Reddy, S. Paddi Fluorescence in the $B^{3}\Pi_{u} (0^{+}) - X^{1}{\Sigma^{+}}_{g}$ system of $I_{2}$, excited by $5145 \AA$ line of $Ar^{+}$ laser operating in single mode, was recorded photoelectrically on a SPEX double monochromator equipped with holographic gratings. The intensities of P (17) lines originating from $\nu' = 43$ end with $\nu"" = 0 to 42$ were measured; these measurements cover the R-centroid range from $2.65 to 3.10 \AA$. A standard tungsten lamp was used to calibrate the spectrial response of the spectrometer = photomultiplier combination. The squared transition moment $|M(\bar{R})|^{2}$ obtained in the present work increases from $\bar{R} = 2.65 to 2.85 \AA$ by about 50% and decreases at higher R. This variation of $|M(\bar{R})|^{2}$ with $\bar{R}$ differs considerably from that reported $earlier.^{1,2,3}$ $^{1}$L. Brewer and J. Tellinghuisen, J. Chem. Phys. 56, 3929-3938 (1972). $^{2}$J.B. Koffend, R. Bacis and R.W. Field, J. Chem, Phys, 70, 2366-2372 (1979). $^{3}$T.K. Balasubramanian, G.L. Bhale. M.N. Dixit and N.A. Marasimham, J. Mol. Spectrose. 88, 259-263 (1981). $^{\ast}$ G.L. Bhale is on leave from the Spectroscopy Division, Bhabha Atomic Research Centre, Bombay, India.

LASER EXCITATION SPECTRUM OF THE SCHUMANN-RUNGE (0,12) BAND OF OXYGEN

Imre, D. — 1982-01-01T00:00:00Z

LASER EXCITATION SPECTRUM OF THE SCHUMANN-RUNGE (0,12) BAND OF OXYGEN Imre, D.; Katayama, D. H.; Kinsey, J. L.; Field, R. W. Although the Schumann-Runge system, $B^{3}{\Sigma^{-}}_{u}- X^{3}{\Sigma^{-}}_{g}$, is the most studied electronic transition of $O_{2}$, its spectroscopy and predissociation mechanisms are still not very well known, We used a pulsed, tunable dye laser to obtain a high resolution scan of the B-X (0,12) band of vibrationally excited $O_{2}$ formed by photodissociation of ozone ar 266 nm, the fourth harmonic of a Nd:YAG laser. The triplet splitting due to spin interactions for a number of rotational levels is observed for the first time and rotational levels up to N"" = 47 have been recorded. The broadened rotational lines indicate that the predissociation rate for the $\nu' = 0$ level is much higher than previous estimates.