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The time evolution of the velocity distribution of hydrogen atoms in a bath gas

Journal Article · · Journal of Chemical Physics; (USA)
DOI:https://doi.org/10.1063/1.457253· OSTI ID:5017565
; ;  [1]
  1. Department of Chemistry, Columbia University, New York, New York 10027 (US)
In this work we probe an ensemble of energetic hydrogen atoms dilutely dispersed in a bath gas which is at thermal equilibrium. A recently developed laser-induced fluorescence technique allows a quantitative measurement on a nanosecond time scale of the shape of a Doppler-broadened absorption line of hydrogen atoms. A nonequilibrium distribution of H atoms is generated by photodissociation, and the line shape is then measured at a flxed time delay as a function of buffer gas pressure. The buffer gases used are He, Ar, Kr, Xe, O{sub 2}, and N{sub 2}. A technique perfected by Shizgal is used to integrate the linearized Boltzmann equation for a hard-sphere potential. The experimental results for the decay of the kinetic energy are fit with cross sections of 10{plus minus}2, 9{plus minus}2, 12{plus minus}2, and 16(+8{minus}4) A{sup 2} for He, Ar, Kr, and Xe, respectively.
OSTI ID:
5017565
Journal Information:
Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 91:12; ISSN JCPSA; ISSN 0021-9606
Country of Publication:
United States
Language:
English