Electron impact dissociation of molecular hydrogen and deuterium: Production of atomic hydrogen and deuterium. cap alpha. ,. beta. , and. gamma. Balmer lines

Journal Article · Tue Jun 01 04:00:00 EDT 1976 · Phys. Rev., A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.13.1989· OSTI ID:7285619

Khayrallah, G A

The absolute cross section for production of atomic Balmer ..cap alpha.., ..beta.., and ..gamma.. radiation by dissociative electron collisions with molecular hydrogen and molecular deuterium has been measured from threshold to 540 eV. Also measured are some absolute cross sections for the excitation of a few molecular lines. All of the cross sections for dissociation show some structure just above threshold. Below this structure, dissociative excitation is interpreted as proceeding through both predissociation and direct dissociation via a bound state above the dissociation limit of the molecule. Above this structure, dissociation proceeds through production of the unbound doubly excited /sup 1/..sigma../sup +//subg/ and /sup 3/..sigma../sup +//subu/ states of H/sub 2/. It is also argued that excitation of these doubly excited states is the major channel for production of excited atomic states in addition to being the major channel for production of protons by electron collisions with the molecule. Indeed its relative contribution increases with an increase of the principal quantum n. This contribution follows an inverse power law of 5.0 +- 0.5. Dissociation via the bound states depends on n with an inverse power law of 6.5 +- 1.0. The cross sections for production of excited deuterium atoms were found to be less than those for production of excited hydrogen atoms in the corresponding states, and the ratio varied from approx. 0.5 below 30 eV to approx. 0.82 at high energies, again indicative of three competing processes for dissociative excitation of the molecular target gas. (AIP)

• Research Organization: Joint Institute for Laboratory Astrophysics, University of Colorado and National Bureau of Standards, Boulder, Colorado 80309
• OSTI ID: 7285619
• Journal Information: Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 13:6; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
BALMER LINES
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
DEUTERIUM
DISSOCIATION
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELEMENTS
ENERGY RANGE
EV RANGE
EV RANGE 10-100
EV RANGE 100-1000
FLUIDS
HYDROGEN
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
MOLECULE COLLISIONS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
STABLE ISOTOPES
TOTAL CROSS SECTIONS