Coupled-channel study of rotational excitation of a rigid asymmetric top by atom impact: (H/sub 2/CO,He) at interstellar temperatures. [cross section convergence, quantum mechanics, pumping model, resonance, Maxwell--Boltzmann distribution, statistical, equilibrium]

Journal Article · Wed Sep 15 00:00:00 EDT 1976 · J. Chem. Phys.; (United States)

OSTI ID:7342779

Garrison, B J; Lester, Jr, W A

A quantum mechanical scattering study is carried out to test a collisional pumping model for cooling the 6 and 2 cm doublets of interstellar formaldehyde. The Arthurs and Dalgarno formalism is extended to the collision of an s-state atom with a rigid asymmetric top molecule and applied to rotational excitation of ortho formaldehyde by helium impact. Using a previously determined configuration interaction potential energy surface, the coupled-channel (CC) equations are integrated at 12 scattering energies between 20 and 95degreeK. Up to 16 ortho formaldehyde states, yielding a maximum of 62 CC equations, are retained to test convergence of computed cross sections. Resonance structure is obtained at approx.20.2, 32.7, and 47.7degreeK. The computed inelastic cross sections are averaged over a Maxwell--Boltzmann distribution and the resultant rates used to solve the equations of statistical equilibrium for the relative populations. The 6 and 2 cm doublets are found to be cooled only upon inclusion of the j=3 doublet. (AIP)

• Research Organization: Department of Chemistry and Inorganic Materials Research Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• OSTI ID: 7342779
• Journal Information: J. Chem. Phys.; (United States), Vol. 65:6
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
FORMALDEHYDE
ATOM-MOLECULE COLLISIONS
HELIUM
INTERSTELLAR SPACE
EXCITATION
ROTATIONAL STATES
ALDEHYDES
ATOM COLLISIONS
COLLISIONS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
MOLECULE COLLISIONS
NONMETALS
ORGANIC COMPOUNDS
RARE GASES
SPACE
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena