Quenching of H{sub 2} Vibrations in Ultracold {sup 3}He and {sup 4}He Collisions
- Institute for Theoretical Atomic and Molecular Physics, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States)
We present results of quantum mechanical scattering calculations including full rovibrational coupling on the relaxation of vibrationally excited H{sub 2} molecules in collision with ultracold {sup 3}He and {sup 4}He atoms. The exothermic vibrational deactivation cross sections exhibit minima at translational temperatures near 10 K and show an inverse velocity dependence in accordance with Wigner{close_quote}s threshold law in the limit of zero kinetic energy. The corresponding rate coefficients exhibit minima before attaining constant values below 10{sup {minus}3} K. The rate coefficients increase by 3 orders of magnitude when the initial vibrational level of the molecule is raised from v=1 to v=10 . The results suggest that quasibound resonance states of {sup 3}HeH{sub 2} and {sup 4}HeH{sub 2} exist, associated with each excited vibrational state of H{sub 2} , and that both the triatomic species {sup 3}HeH{sub 2} and {sup 4}HeH{sub 2} have one bound vibrational state. {copyright} {ital 1998} {ital The American Physical Society}
- OSTI ID:
- 601012
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 15 Vol. 80; ISSN 0031-9007; ISSN PRLTAO
- Country of Publication:
- United States
- Language:
- English
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