Rovibrational excitation in collisions of He onD2at energies less than 2 keV
| Autor: | Arnold Russek, Paul Muchnick |
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| Rok vydání: | 1994 |
| Předmět: | |
| Zdroj: | Physical Review A. 49:1757-1766 |
| ISSN: | 1094-1622 1050-2947 |
| DOI: | 10.1103/physreva.49.1757 |
| Popis: | 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 ismore » obtained with experimental measurements on rovibrational excitation energies produced in quasielastic collisions of He on D{sub 2}« less |
| Databáze: | OpenAIRE |
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