FIR SPECTROSCOPY OF BARE CH$_5^+$ USING LASER INDUCED REACTIONS
Loading...
Date
2005
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Laser Induced Reaction (LIR) is a novel technique for the spectroscopy of molecular ions as well as the study of state-specific rate coefficients and lifetimes of excited states. It is based on trapping mass-selected ions in the cold environment of a reactant gas and probing the laser-induced excitation of the ion by the outcome of the corresponding endothermic ion-molecule reaction. The feasibility of this method has been demonstrated in the past for the % %\begin{wrapfigure}{c}{70mm} %\includegraphics[width=70mm]{Fig1} % aption{Measured and calculated spectra of CH$_5^+$} %\end{wrapfigure} % % electronic spectroscopy of N$_2^+$ in the charge transfer reaction with Ar, and the spectroscopy of the IR-active modes of the acetylene cation in the abstraction reaction of C$_2$H$_2^+$ with hydrogen}, 2068--2075 (2002)}}, 073001, (2005)}.\\ % Recently, LIR has been applied to record the first far infrared spectra of bare CH$_5^+$ and some of its deuterated versions combining a low temperature 22--pole ion trap with the large tuning range of the free electron laser \mbox{FELIX}. % }, 134--141 (2005)}. To obtain the LIR spectrum, the product ions of the endothermic proton transfer reaction CH$_5^+$ + CO$_2$ $\longrightarrow$ CH$_4$ + OCOH$^+$ have been counted as a function of the \mbox{FELIX} wavelength. In addition to the earlier observed C--H-stretching feature}, 135--137 (1999)} at 3000 cm$^{-1}$, low-frequency extensions down to 2200 cm$^{-1}$ become discernible, as well as a H--C--H bending feature at 1250 cm$^{-1}$. Comparison of the measured data to computed ones shows that CH$_5^+$ is fluxional at the temperature of the experiment, $T$=110K.
Description
{S. Schlemmer, E. Lescop, J. v. Richthofen, and D. Gerlich, J. Chem. Phys. {\bf 117{O. Asvany, T. Giesen, B. Redlich, and S. Schlemmer, Phys. Rev. Lett. {\bf 94{S. Schlemmer and O. Asvany, J. Phys.: Conf. Ser. {\bf 4{E. T. White, J. Tang, and T. Oka, Science {\bf 284
Author Institution: Leiden Observatory, P.O. Box 9513, 2300 RA Leiden, The Netherlands; I. Physikalisches Institut, Universitat zu Koln,; Zulpicher Stra{\ss}e 77, 50937 Koln, Germany
Author Institution: Leiden Observatory, P.O. Box 9513, 2300 RA Leiden, The Netherlands; I. Physikalisches Institut, Universitat zu Koln,; Zulpicher Stra{\ss}e 77, 50937 Koln, Germany