			15min:

VIBRATIONAL SPECTROSCOPY OF ATMOSPHERIC RELEVANT HALOGENATED HYDROCARBONS: THE C-H-STRETCH VIBRATIONS OF CHLOROMETHYL.

A. C. BLAIR, T. HÄBER AND D. J. NESBITT, JILA, University of Colorado, Boulder, Colorado 80309-0440.

The symmetric stretch vibration (3055.07723(63) cm^-1)of chloromethyl radical has been characterized via tunable difference frequency IR absorption spectroscopy in a slit supersonic discharge expansion source with a resolution of 0.0001 cm^-1. Rotational progressions for both nuclear spin isomers (K = 0,1) and chlorine isotopes are observed and assigned. Rotational analysis and least squares fits to a Watson Hamiltonian have been performed with ground state values were taken from rotational spectra, yielding asymmetric top rotational, centrifugal distortion constants and isotope shifts for the vibrationally excited state. Searches at shot noise limited detection sensitivity have also been performed for the asymmetric C-H-stretch vibration (3163-3232 cm^-1), confirming theoretical predictions that this band is at least 25 times weaker then the corresponding symmetric stretch vibration.