10min:
DISTRIBUTION OF INTERNAL STATES OF CO AND OH FROM O(1D) + C6H6 AND C6D6 DETERMINED WITH TIME-RESOLVED FOURIER-TRANSFORM SPECTROSCOPY.

HUI-FEN CHEN, National Tsing Hua University, Departmeny of Chemistry, Hsinchu 30013, Taiwan; AND YUAN-PERN LEE, National Chiao Tung University, Department of Applied Chemistry, Hsinchu 30010, Taiwan, and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.

Rotationally resolved infrared emission spectra of CO (1\leq v \leq 6) in the spectral region 1800 -- 2350 cm-1 and OH (1\leq v \leq 3) in the region 2800 -- 3700 cm-1 were recorded with a step-scan Fourier-transform spectrometer. CO shows a rotational distribution corresponding approximately to temperatures 1520 K for v = 1 and 860 K for v = 2 -- 6, with an average rotational energy of 9\pm1 kJ mol-1 at the earliest applicable period (2.5 -- 7.5 µs) upon photolysis. Extrapolation to time zero based on data in the range 2.5 -- 27.5 µs yields an average nascent rotational energy of 14\pm4 kJ mol-1. Observed vibrational distribution of CO corresponds to a vibrational temperature of 5800\pm330 K and an average vibrational energy of 33\pm3 kJ mol-1. OH shows a rotational distribution corresponding to temperatures ~550 K for the P1 branch (v = 1 -- 3) and ~620 K for the P2 branch (v = 1 -- 3), with an average nascent rotational energy of 4\pm1 kJ mol-1. The observed vibrational temperature of OH is 4830\pm230 K, corresponding to an average vibrational energy of 21\pm4 kJ mol-1. The branching ratio of [CO]/[OH] is ~2.1\pm0.1 for O (1D) + C6H6 and no OD was observed from O (1D) + C6D6. The significant deuterium isotope effect will be discussed.