Vibrational energy transfer from highly excited anharmonic oscillators. Dependence on quantum state and interaction potential

Journal Article · Tue Jun 15 00:00:00 EDT 1982 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.442954· OSTI ID:5167516

Nesbitt, D J; Hynes, J T

In order to elucidate the general features of vibrational deactivation of highly excited anharmonic oscillators, we present quasiclassical trajectory calculations on prototype collinear I/sub 2/ (v)-inert gas collision systems. The results for vibrational-translational energy transfer reveal several interesting trends as a function of initial vibrational quantum state, projectile mass, and projectile--oscillator interaction potential. (1) Vibrational deactivation is inefficient from all quantum levels and for all projectile masses. The average energy transfer per collision ..delta..E is strongly peaked at intermediate vibrational levels (vroughly-equal80) and is observed to be at most roughly-equal-k/sub b/T. Furthermore, when scaled to h..omega..(E), the ''local'' oscillator energy spacing, ..delta..E can be accurately represented by a simple power law in vibrational quantum number over a wide range of bound states. (2) Energy transfer is progressively less efficient from levels in the neighborhood of and approaching dissociation. (3) Vibrational energy loss for high levels of initial vibrational excitation (v>90) is rather insensitive to the nature of the interaction potential. Smooth exponential and hard-sphere interaction results differ by less than an order of magnitude. This observed insensitivity motivates the development of an analytic collision model, in which simple hard-sphere geometry and dynamics are used to calculate ..delta..E. The model results are in qualitatively good agreement with trajectory calculations and also indicate that nonuniform sampling of the anharmonic oscillator velocity and phase are responsible for decreased energy transfer efficiency from high vibrational states.

• Research Organization: Department of Chemistry, University of Colorado, Boulder, Colorado 80309
• OSTI ID: 5167516
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 76:12; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ANHARMONIC OSCILLATORS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
COLLISIONS
ELECTRONIC EQUIPMENT
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
EQUIPMENT
EXCITED STATES
FLUIDS
GASES
HALOGENS
IODINE
MATHEMATICAL MODELS
MOLECULE COLLISIONS
NONMETALS
OSCILLATORS
RARE GASES
VIBRATIONAL STATES