15min:

CHIA-SHIH LIN, YING-EN CHEN AND BOR-CHEN CHANG, Department of Chemistry, National Central University, Chung-Li 32054,Taiwan.

We have successfully acquired new dispersed fluorescence spectra following the excitation of several à X vibronic bands of HCCl and DCCl at visible wavelengths in a discharge free jet expansion using an intensified charge-coupled device (ICCD) detector. The new dispersed fluorescence spectra reveal more details of the X¹A' state vibrational structure in these molecules than our previous reports.^, Complete vibrational parameters including fundamental frequencies, anharmonicities, and coupling constants were determined for the HCCl/DCCl X¹A' state. Furthermore, perturbations from the background triplet state (ã³A'') were clearly observed in the new dispersed fluorescence spectra, and therefore the singlet-triplet energy gap could be determined. Additionally, a couple of new à X vibronic bands were found in the laser excitation spectra of HCCl and DCCl. The rotationally resolved excitation spectra of a few HC³⁵Cl à X vibronic bands and those of HC³⁷Cl were recorded and analyzed. Our progress on the experiments and analyses will be presented.