15min:

C. MUKARAKATE, C. TAO AND S. A. REID, Department of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, WI 53201-1881.

We report on single vibronic level (SVL) emission spectra from bands in the progressions 2₀ⁿ, 2₀ⁿ3₀^m, 1₀¹2₀ⁿ, and 1₀¹2₀ⁿ3₀¹ in the A¹A''-X¹A' system of CH³⁵Cl, CH³⁷Cl, CD³⁵Cl and CD³⁷Cl. As in previous studies of CHF/CDF and CHBr/CDBr, the carbenes were generated using a pulsed discharge source, and SVL emission spectra obtained using a 0.3 m spectrograph in combination with a gated, intensified CCD detector. These spectra reveal rich new detail regarding the vibrational structure of the X¹A' and a³A'' states, and spin-orbit induced mixing between them, up to 9000 cm^-1 above the vibrationless level of the X¹A' state. For CHCl, we observe around three times the number of X¹A' levels previously reported,, and a number of new a³A'' state levels. The results of Dunham expansion fits to the vibrational term energies, and comparisons with previous experimental and recent high quality theoretical studies^, will be reported. Overall, the derived vibrational parameters of the X¹A' and a³A'' states are in excellent agreement with ab initio predictions, including our own DFT calculations.