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

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.457729· OSTI ID:6974398

Gordon, R J ^[1]

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1. Department of Chemistry, University of Illinois at Chicago, Box 4348, Chicago, Illinois 60680 (USA)

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.

• OSTI ID: 6974398
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 92:7; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
640302 -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
ENERGY LEVELS
ENERGY TRANSFER
EXCITED STATES
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
MOLECULES
POLYATOMIC MOLECULES
RELAXATION
VIBRATIONAL STATES