Rate constants for rotational excitation in NH/sub 3/--He collisions

Journal Article · Fri Sep 15 04:00:00 EDT 1978 · J. Chem. Phys.; (United States)

OSTI ID:6733728

Davis, S L; Boggs, J E

The semiclassical method (classical translational motion and quantum mechanical rotational motion) is used to calculate cross sections and rate constants for (J< or =3, K) ..-->.. (J< or =4, K) rotational excitations in NH/sub 3/--He collisions on Green's uniform electron gas (Gordon--Kim) potential surface. The assumptions involved in the use of the rigid rotor approximation for the inversion motion are examined in some detail. Agreement between semiclassical and accurate close-coupling cross sections is good, comparable to the agreement between the coupled-states and the close-coupling cross sections. A ''semiclassical coupled-states'' approximation was found to give reliable cross sections except at low energies. Microwave double resonance ..delta..I/I values were calculated from the rate constants and compared with experiment. Good agreement was found for the ..delta..k=3 transitions, but poor agreement for the ..delta..k=0 transitions. Possible explanations for the discrepancies are discussed.

• Research Organization: Department of Chemistry, The University of Texas, Austin, Texas 78712
• OSTI ID: 6733728
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 69:6; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular &amp; Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AMMONIA
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
FLUIDS
HELIUM
HYDRIDES
HYDROGEN COMPOUNDS
MOLECULE COLLISIONS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
RARE GASES
ROTATIONAL STATES