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Title: Temperature-dependent relaxation of CO(v=1) by HD, D/sub 2/, and He and of D/sub 2/(v=1) by D/sub 2/

Abstract

Rate constants for the vibrational deactivation of CO in collisions with HD, D/sub 2/, and He have been measured as a function of temperature using the laser excited vibrational fluorescence technique. Throughout the 109--630 degreeK range, CO--He and CO--HD samples exhibit a single exponential decay, dominated by V--T,R transfer, with rates increasing rapidly with temperature. Typical collision deactivation rate constants at 630 degreeK are 22.7 sec/sup -1/ torr/sup -1/ for He and 82.5 sec/sup -1/ torr/sup -1/ for HD, and, at 109 degreeK, 0.067 sec/sup -1/ torr/sup -1/ for He and 0.27 sec/sup -1/ torr/sup -1/ for HD. At low temperatures, diffusion and radiative decay become important contributions to the observed rates. In CO--D/sub 2/ mixtures, double exponential decay of CO fluorescence at large D/sub 2/ mole fractions is obtained, corresponding to rapid V--V transfer between the (v=1) vibrational levels of CO and D/sub 2/, followed by coupled V--T,R deactivation. The V--V transfer rate (..delta..E=-850 cm/sup -1/) increases from 0.26 sec/sup -1/ torr/sup -1/ at 202 degreeK to 69.4 sec/sup -1/ torr/sup -1/ at 633 degreeK. The V--T,R deactivation rate constant for excited CO by D/sub 2/ is significantly slower than that by HD and H/sub 2/, going from 0.089more » sec/sup -1/ torr/sup -1/ at 156 degreeK to 3.7 sec/sup -1/ torr/sup -1/ at 450 degreeK, indicating the decreased importance of the rotational states of D/sub 2/ in the deactivation of CO than hypothesized for H/sub 2/ and HD. The deactivation of excited D/sub 2/ by collisions with D/sub 2/ also increases with temperature, ranging from 0.080 sec/sup -1/ torr/sup -1/ at 202 degreeK to 6.9 sec/sup -1/ torr/sup -1/ at 450 degreeK. (AIP)« less

Authors:
; ; ;
Publication Date:
Research Org.:
Department of Chemistry, Georgetown University, Washington, D.C. 20057
OSTI Identifier:
7175531
Resource Type:
Journal Article
Journal Name:
J. Chem. Phys.; (United States)
Additional Journal Information:
Journal Volume: 65:4
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; CARBON MONOXIDE; ATOM-MOLECULE COLLISIONS; MOLECULE-MOLECULE COLLISIONS; DEUTERIUM; HELIUM; HYDROGEN DEUTERIDE; ENERGY TRANSFER; RELAXATION; VIBRATIONAL STATES; ATOM COLLISIONS; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; COLLISIONS; CRYOGENIC FLUIDS; DEUTERIDES; DEUTERIUM COMPOUNDS; ELEMENTS; ENERGY LEVELS; EXCITED STATES; FLUIDS; HYDROGEN COMPOUNDS; HYDROGEN ISOTOPES; ISOTOPES; LIGHT NUCLEI; MOLECULE COLLISIONS; NONMETALS; NUCLEI; ODD-ODD NUCLEI; OXIDES; OXYGEN COMPOUNDS; RARE GASES; STABLE ISOTOPES; 640304* - Atomic, Molecular & Chemical Physics- Collision Phenomena

Citation Formats

Drozdoski, W S, Young, R M, Bates, Jr, R D, and Hancock, J K. Temperature-dependent relaxation of CO(v=1) by HD, D/sub 2/, and He and of D/sub 2/(v=1) by D/sub 2/. United States: N. p., 1976. Web.
Drozdoski, W S, Young, R M, Bates, Jr, R D, & Hancock, J K. Temperature-dependent relaxation of CO(v=1) by HD, D/sub 2/, and He and of D/sub 2/(v=1) by D/sub 2/. United States.
Drozdoski, W S, Young, R M, Bates, Jr, R D, and Hancock, J K. Sun . "Temperature-dependent relaxation of CO(v=1) by HD, D/sub 2/, and He and of D/sub 2/(v=1) by D/sub 2/". United States.
@article{osti_7175531,
title = {Temperature-dependent relaxation of CO(v=1) by HD, D/sub 2/, and He and of D/sub 2/(v=1) by D/sub 2/},
author = {Drozdoski, W S and Young, R M and Bates, Jr, R D and Hancock, J K},
abstractNote = {Rate constants for the vibrational deactivation of CO in collisions with HD, D/sub 2/, and He have been measured as a function of temperature using the laser excited vibrational fluorescence technique. Throughout the 109--630 degreeK range, CO--He and CO--HD samples exhibit a single exponential decay, dominated by V--T,R transfer, with rates increasing rapidly with temperature. Typical collision deactivation rate constants at 630 degreeK are 22.7 sec/sup -1/ torr/sup -1/ for He and 82.5 sec/sup -1/ torr/sup -1/ for HD, and, at 109 degreeK, 0.067 sec/sup -1/ torr/sup -1/ for He and 0.27 sec/sup -1/ torr/sup -1/ for HD. At low temperatures, diffusion and radiative decay become important contributions to the observed rates. In CO--D/sub 2/ mixtures, double exponential decay of CO fluorescence at large D/sub 2/ mole fractions is obtained, corresponding to rapid V--V transfer between the (v=1) vibrational levels of CO and D/sub 2/, followed by coupled V--T,R deactivation. The V--V transfer rate (..delta..E=-850 cm/sup -1/) increases from 0.26 sec/sup -1/ torr/sup -1/ at 202 degreeK to 69.4 sec/sup -1/ torr/sup -1/ at 633 degreeK. The V--T,R deactivation rate constant for excited CO by D/sub 2/ is significantly slower than that by HD and H/sub 2/, going from 0.089 sec/sup -1/ torr/sup -1/ at 156 degreeK to 3.7 sec/sup -1/ torr/sup -1/ at 450 degreeK, indicating the decreased importance of the rotational states of D/sub 2/ in the deactivation of CO than hypothesized for H/sub 2/ and HD. The deactivation of excited D/sub 2/ by collisions with D/sub 2/ also increases with temperature, ranging from 0.080 sec/sup -1/ torr/sup -1/ at 202 degreeK to 6.9 sec/sup -1/ torr/sup -1/ at 450 degreeK. (AIP)},
doi = {},
url = {https://www.osti.gov/biblio/7175531}, journal = {J. Chem. Phys.; (United States)},
number = ,
volume = 65:4,
place = {United States},
year = {1976},
month = {8}
}