On the theory of H + OH/2Pi/ collisions and interstellar OH maser action

Journal Article · Sat Sep 01 04:00:00 EDT 1979 · J. Chem. Phys.; (United States)

OSTI ID:5129091

Shapiro, M; Kaplan, H

The role of H atom collisions as a pump for the 18 cm OH maser lines in interstellar sources is considered. Theory of 2Pi molecules with a doublet-state atom is formulated, and expressions for the interaction matrix between the sublevels of the H(2S) + OH(2Pi) system are derived and correlated to the H/sub 2/O Born-Oppenheimer states. The interaction matrix thus derived is used to obtain cross-sections and rate constants between the j 3/2 and j 5/2 rotational manifolds. Selectivity of the H + OH collision is discussed, and the collisional rate constants are used in a simple cloud model in which radiative decay and effects of background radiation are also incorporated. The model is solved for a wide range of H atom densities. Nonthermal, and often inverted Lambda level populations were shown to exist for a variety of kinetic temperatures and densities, suggesting that collisions with H serve as a major pump source of all four 18 cm emission lines.

• Research Organization: Weizmann Institute of Science, Rehovot, Israel
• OSTI ID: 5129091
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 71; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

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640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLIFIERS
ANGULAR MOMENTUM
ANIONS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
BORN-OPPENHEIMER APPROXIMATION
CHARGED PARTICLES
COLLISIONS
ELECTRONIC EQUIPMENT
ELEMENTS
EMISSION SPECTRA
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EQUIPMENT
EXCITATION
EXCITED STATES
HYDROGEN
HYDROGEN COMPOUNDS
HYDROXIDES
HYPERFINE STRUCTURE
INTERSTELLAR SPACE
IONS
KINETICS
MASERS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
MOLECULE COLLISIONS
NONMETALS
OXYGEN COMPOUNDS
REACTION KINETICS
ROTATIONAL STATES
SPACE
SPECTRA
WATER