The Journal of Chemical Physics

Collisional excitation of CO2(0111) by hot hydrogen atoms: Alternating intensities in state-resolved vibrational, rotational, and translational energy transfer

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Time domain tunable diode laser absorption spectroscopy has been used to measure rotationally resolved transient absorption line shapes and nascent rotational populations for CO2 molecules excited into the (01 11) vibrational state by collisions with translationally hot hydrogen atoms. The even rotational levels are more heavily populated than the odd levels, in agreement with propensity rules derived earlier by Alexander and Clary. The nascent populations and transient linewidths are interpreted in terms of a theoretical model that lends insight into the H-CO2 collision dynamics. The cross section for exciting (0111) is ~∼.23 times the cross section for exciting (0001), and ∼0.38 times the cross section for exciting (1000). © 1990 American Institute of Physics.