Theory of chemical reactions of vibronically excited H/sub 2/(B /sup 1/. sigma. /sup +//sub u/). II. Noble gas dihydrides
The recently discovered chemically bound excited state of HeH/sub 2/ from large MRD--CI calculations can be explained in terms of the highly ionic character of the H/sub 2/B /sup 1/..sigma../sup +//sub u/ excited state at R = 4.0 a.u. and the resulting binding between it and the polarized He via electrostatic and overlap (with the diffuse ''H /sup -/'' center) effects. Based on this explanation, a theory for chemical reactions of normally nonreactive systems is proposed. These reactions may occur when one of the reacting molecules is excited vibronically to a state of maximum ionicity. The H/sub 2/B /sup 1/summation/sup +//sub u/ state presents a convenient test case. State-specific, open shell SCF calculations have been carried out for the He+H(/sub 2/, Ne+H(/sub 2/, and Ar+H(/sub 2/ systems. The results for He+H(/sub 2/ agree with the MRD--CI calculations and demonstrate that electron correlation is reasonably constant over the potential energy surface. NeH(/sub 2/ and ArH(/sub 2/ molecules are predicted for the first time to bind chemically in an excited /sup 1/A' state at geometries similar to HeH(/sub 2/ and close to a crossing with the unbound ground state into which they can decay radiatively or via nonadiabatic coupling. Our results suggest that, in accordance with the previous observations by Fink et al. (J. Chem. Phys. 56, 900 (1972)) of quenching of fluorescence of the H/sub 2/B /sup 1/..sigma../sup +//sub u/..-->..X /sup 1/..sigma../sup +//sub g/ transition in a He+H(/sub 2/ system, quenching should be observed in Ne+H(/sub 2/ and Ar+H(/sub 2/ systems, but this time for higher vibrational numbers.
- Research Organization:
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Vas. Constantinou 48, Athens 501/1, Greece
- OSTI ID:
- 5122702
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 80:5
- Country of Publication:
- United States
- Language:
- English
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ARGON
CHEMICAL REACTIONS
HELIUM
HYDROGEN
EXCITED STATES
NEON
ARGON HYDRIDES
BINDING ENERGY
ELECTRON CORRELATION
HELIUM HYDRIDES
NEON HYDRIDES
SELF-CONSISTENT FIELD
VIBRATIONAL STATES
ARGON COMPOUNDS
CORRELATIONS
ELEMENTS
ENERGY
ENERGY LEVELS
FLUIDS
GASES
HELIUM COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
NEON COMPOUNDS
NONMETALS
RARE GAS COMPOUNDS
RARE GASES
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory