Excimer Laser Photolysis Studies of Translational-to-Vibrational Energy Transfer in Collisions of H and D Atoms with CO
COLORADO UNIV AT BOULDER DEPT OF CHEMISTRY
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Translational-to-vibrational excitation of carbon monoxide is observed as a result of collisions of high energy H and D atoms with CO. The fast atoms are produced by excimer laser photolysis of H2S, D2S, HCl, HBr, or HI at 193 or 248 nm. Detection of time and wavelength-resolved infrared fluorescence is used to quantify the CO vibrational state excitations. The CO v 1 - 6 state distribution from H H1, 193 nm, E sub cm 2.3 eV CO collisions is 0.75 or - 0.15, 0.15 or - 0.01, 0.01 or - 0.02, 0.02 or -1 0.01, and 0.01 or - 0.01. The corresponding state distribution from D D2S, 193 nm, E sub cm 2.2 eV CO is 0.79 or - 0.19, 0.13 or - 0.01, 0.05 or - 0.02, 0.02 or - 0.02, 0.01 or - 0.01, and 0.01 or - 0.01. Rotational excitation is at least as significant as vibrational excitation, based on estimates of the total energy transfer. Measurements of the relative vibrational excitation efficiency as a function of initial H atom energy show that the fraction of translational energy converted to CO vibration increases by more than 300 as the initial H atom energy is increased from 1.0 to 3.2 eV. Good qualitative agreement is found between the experimental results and classical trajectory calculations carried out for collinear collisions of H and D atoms with CO using a simple repulsive interaction potential.
- Atomic and Molecular Physics and Spectroscopy