Rovibrational excitation in collisions of He on D{sub 2} at energies less than 2 keV

Journal Article · Tue Mar 01 04:00:00 EST 1994 · Physical Review A

DOI:https://doi.org/10.1103/PhysRevA.49.1757· OSTI ID:142629

Muchnick, P; Russek, A ^[1]

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1. Department of Physics, The University of Connecticut, Storrs, Connecticut 06269 (United States)

This work presents a theoretical study of rovibrational excitation in electronically elastic collisions of He on either H{sub 2} or D{sub 2} in the collision energy range 100 eV{le}{ital E}{sub inc}{le}2 keV. Earlier classical trajectory collision calculations, which predicted the rovibrational excitation energy to follow a universal scaling law, are here generalized to (1) encompass vibrational excitation caused by a three-body force representing the He interacting with the H{sub 2} covalent bond, and (2) incorporate quantization of vibrational excitation by a semiquantal ansatz imposed on the otherwise classical calculations. Quantization of vibrational excitation is shown to cause a breakdown of the scaling law predicted by the fully classical theory. The collisional excitation calculations utilize straight-line trajectories in the framework of the impulsive approximation, and are based on an improved parametric fit to the {ital ab} {ital initio} interaction energy surface for the HeH{sub 2} triatomic molecular system. In addition to the usual two-body Bohr and Born-Mayer terms describing the He-H interactions, the new interaction potential incorporates a three-body term to describe the contribution arising from the He interacting with the H-H covalent bond. The three-body force gives rise to some vibrational excitation phenomena, which are here explored. Good agreement is obtained with experimental measurements on rovibrational excitation energies produced in quasielastic collisions of He on D{sub 2}

• OSTI ID: 142629
• Journal Information: Physical Review A, Journal Name: Physical Review A Journal Issue: 3 Vol. 49; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ATOM-MOLECULE COLLISIONS
DEUTERIUM
EXCITED STATES
HELIUM
KEV RANGE 01-10
QUASI-ELASTIC SCATTERING
ROTATIONAL STATES
SCALING LAWS
VIBRATIONAL STATES