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Title: The origin of small and large molecule behavior in the vibrational relaxation of highly excited molecules

An explanation is proposed for the qualitatively different types of behavior that have been reported for the vibrational relaxation of highly excited diatomic and polyatomic molecules. It is argued that all of the diatomic molecules that have been studied in bulk relax adiabatically at room temperature. In contrast, large polyatomic molecules have low frequency modes which act at doorway'' modes for the rest of the molecules, producing an impulsive relaxation mechanism. The theoretical work of Nesbitt and Hynes showed that impulsive collisions result in an exponential decay of the average vibrational energy of a Morse oscillator, whereas adiabatic collisions produce nonexponential power law behavior. We propose that this result explains a large body of data for the vibrational relaxation of small and large molecules.
Authors:
 [1]
  1. (Department of Chemistry, University of Illinois at Chicago, Box 4348, Chicago, Illinois 60680 (USA))
Publication Date:
OSTI Identifier:
6974398
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; (USA); Journal Volume: 92:7
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 74 ATOMIC AND MOLECULAR PHYSICS; POLYATOMIC MOLECULES; MOLECULE-MOLECULE COLLISIONS; RELAXATION; ENERGY TRANSFER; EXCITED STATES; VIBRATIONAL STATES; COLLISIONS; ENERGY LEVELS; MOLECULE COLLISIONS; MOLECULES 400201* -- Chemical & Physicochemical Properties; 640302 -- Atomic, Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory