Diode laser probe of CO2 vibrational excitation produced by collisions with hot deuterium atoms from the 193 nm excimer laser photolysis D2S

Publisher Website
Google Scholar
Abstract
The 193 nm excimer laser photolysis of D2S in D2S/CO2 mixtures produces fast deuterium atoms (ETR∼2.2 eV) which vibrationally excite CO2 molecules via inelastic translation–vibration/rotation (T–V/R) energy exchange processes. A high resolution (10−3 cm−1) cw diode laser probe was used to monitor the excitation of ν3 (antisymmetric stretch) and ν2 (bend) vibrations in CO2. The present results are compared with previous experiments involving hot hydrogen atom excitation of CO2 in H2S/CO2 mixtures as well as with theoretical calculations of the excitation probability. The probability for excitation of a ν3 quantum in CO2 is about 1%–2% per gas kinetic D/CO2 collision. Bending (ν2) quanta are produced about eight times more efficiently than antisymmetric stretching (ν3) quanta. The thermalization rate for cooling hot D atoms below the threshold for production of a ν3 vibrational quantum corresponds to less than 2 D*/D2S collisions or 15 D*/CO2 collisions.