Theoretical study of intermolecular energy transfer involving electronically excited molecules: He(/sup 1/S) + H/sub 2/(B /sup 1/. sigma. /sub u//sup +/)
To further understanding of gas-phase collision dynamics involving electronically-excited molecules, a fully quantum-mechanical study of He + H/sub 2/ (B/sup 1/ ..sigma../sub u//sup +/) was undertaken. Iterative natural orbital configuration interaction (CI) calculations were performed to obtain the interaction potential between He and H/sub 2/ (B /sup 1/..sigma../sub u//sup +/). The potential energy surface (PES) is highly anisotropic and has a van der Waals well of about 0.03 eV for C/sub 2v/ approach. Avoided PES crossings occur with He + H/sub 2/ (E,F, /sup 1/..sigma../sub g//sup +/) and with He + H/sub 2/ (X /sup 1/ ..sigma../sub g//sup +/) and cause a local maximum and a deep minimum in the He + H/sub 2/(B /sup 1/..sigma../sub u//sup +/) PES, respectively. The crossing with He + H/sub 2/(X /sup 1/..sigma../sub g//sup +/) provides a mechanism for fluorescence quenching. The computed CI energies were combined with previous multi-reference double excitation CI calculations and fit with analytic functions for convenience in scattering calculations. Accurate dipole polarizabilities and quadrupole moment of H/sub 2/(B/sup 1/ ..sigma../sub u//sup +/) were computed for use in the multipole expansion, which is the analytic form of the long-range PES. Coupled-channel equations for rotational and rovibrational energy transfer were solved to obtain partial, integral, and differential cross sections at scattering energies up to 0.210 eV.
- Research Organization:
- California Univ., Berkeley (USA)
- OSTI ID:
- 7149023
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
CONFIGURATION INTERACTION
CROSS SECTIONS
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
ENERGY TRANSFER
EV RANGE
EXCITED STATES
FLUIDS
GASES
HELIUM
HYDROGEN
INTERMOLECULAR FORCES
MECHANICS
MILLI EV RANGE
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
NONMETALS
QUANTUM MECHANICS
RARE GASES