SINGLE VIBRONIC LEVEL EMISSION SPECTROSCOPY OF CHCl AND CDCl: VIBRATIONAL STRUCTURE OF THE $X$$^{1}A^{\prime}$ AND $a$$^{3}A^{\prime\prime}$ STATES

Abstract

Author Institution: Department of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, WI 53201-1881We report on single vibronic level (SVL) emission spectra from bands in the progressions 2$_0^{n}$, 2$_0^{n}$3$_0^{m}$, 1$_0^{1}$2$_0^{n}$, and 1$_0^{1}$2$_0^{n}$3$_0^{1}$ in the $A$$^{1}A^{\prime\prime}$-$X$$^{1}A^{\prime}$ system of CH$^{35}$Cl, CH$^{37}$Cl, CD$^{35}$Cl and CD$^{37}$Cl. 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 $X$$^{1}A^{\prime}$ and $a$$^{3}A^{\prime\prime}$ states, and spin-orbit induced mixing between them, up to 9000 cm$^{-1}$ above the vibrationless level of the $X$$^{1}A^{\prime}$ state. For CHCl, we observe around three times the number of $X$$^{1}A^{\prime}$ levels previously reported,}, and a number of new $a$$^{3}A^{\prime\prime}$ state levels. The results of Dunham expansion fits to the vibrational term energies, and comparisons with previous experimental and recent high quality theoretical studies}$^{,}$} will be reported. Overall, the derived vibrational parameters of the $X$$^{1}A^{\prime}$ and $a$$^{3}A^{\prime\prime}$ states are in excellent agreement with $ab$ $initio$ predictions, including our own DFT calculations