MCSCF characterization of the HeH/sub 2//sup +/ 2 /sup 2/A/sub 1/(/sup 2/. sigma. /sup +/) polarization state. A radiative mechanism for the production of H/sub 2//sup +/ from thermal He/sup +/+H/sub 2/ collisions

Journal Article · Wed Oct 01 00:00:00 EDT 1980 · J. Chem. Phys.; (United States)

OSTI ID:5096081

Hopper, D G

A quantitative multiconfiguration self-consistent field treatment of the potential curves for the C/sub 2v/ and C/sub infinityv/ approach of an He/sup +/(1 /sup 2/S) ion to H/sub 2/(X /sup 1/..sigma../sub g//sup +/) has been made. Second-root same-symmetry orbital optimization techniques were employed in order to treat the 2 /sup 2/A/sub 1/(2 /sup 2/A',2 /sup 2/..sigma../sup +/) state involved. These computations have established that the shallow He/sup +/--H/sub 2/ ion--molecule polarization well is characterized by a C/sub 2v/ minimum with the attributes (E/sub b/, R/sup e/2, R/sup e/2) 0.091 eV, 2.345 =(A-circle, 0.714 A). The fundamental vibrational frequency for the pseudodiatomic He/sup +/--H/sub 2/ is 284 cm/sup -1/. As R2 decreases further the difference between the C/sub infinityv/ and C/sub 2v/ cut narrows as the system approaches the high interaction region. The availability of this polarization state suggests a collisional--radiative mechanism for the production of H/sub 2//sup +/ from the reaction of He/sup +/(1 /sup 2/S) with H/sub 2/(X /sup 1/..sigma../sub g//sup +/) at thermal energies, with or without a third body M He/sup +/(1 /sup 2/S)+H/sub 2/(X /sup 1/..sigma../sub g//sup +/) /sup M/..-->.. He/sup +/--H/sub 2/(2 /sup 2/A/sub 1/) He/sup +/--H/sub 2/(2 /sup 2/A/sub 1/)..-->..(He--H/sub 2//sup +/(1 /sup 2/A/sub 1/))/sup /+h..nu..(153 nm) (He--H/sup +//sub 2/(1 /sup 2/A/sub 1/))/sup /..-->..He(1 /sup 1/S)+H/sup +//sub 2/ (X /sup 2/..sigma../sub g//sup +/,v)+KE. The polarization state also provides a thermal pathway for vibrational deactivation of hydrogen by helium ions. These thermal mechanisms are discussed in relation to the well-known tunneling mechanism yielding H/sup +/ and with regard to planetary and interstellar chemistry.

• Research Organization: Theoretical Chemistry Group, JAYCOR, P.O. Box 3126, Dayton, Ohio 45431
• OSTI ID: 5096081
• Journal Information: J. Chem. Phys.; (United States), Vol. 73:7
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
HELIUM HYDRIDES
EXCITED STATES
HELIUM IONS
ION-MOLECULE COLLISIONS
HYDROGEN
SELF-CONSISTENT FIELD
CHARGED PARTICLES
COLLISIONS
ELEMENTS
ENERGY LEVELS
HELIUM COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
ION COLLISIONS
IONS
MOLECULE COLLISIONS
NONMETALS
RARE GAS COMPOUNDS
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena