Excimer laser photolysis studies of translationalhyphen;tohyphen;vibrational energy transfer in collisions of H and D atoms with CO

摘要

Translationalhyphen;tohyphen;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, D2,S, HCl, HBr, or HI at 193 or 248 nm. Detection of time and wavelengthhyphen;resolved infrared fluorescence is used to quantify the CO vibrational state excitation. The CO (v=1minus;6) state distribution from H (H2S, 193 nm,Ecm=2.3 eV) +CO collisons is 0.74plusmn;0.15, 0.15plusmn;0.01, 0.08plusmn;0.01, 0.01plusmn;0.01, 0.02plusmn;0.01, and 0.01plusmn;0.01. The corresponding state distribution from D (D2S, 193 nm,Ecm=2.2 eV)+CO is 0.79plusmn;0.19, 0.13plusmn;0.01, 0.05plusmn;0.02, 0.02plusmn;0.02, 0.01plusmn;0.01, and 0.01plusmn;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 300percnt; 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.