Chemi-ionization in collisions of metastable helium with metastable helium

Journal Article · Thu Jun 01 00:00:00 EDT 1978 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.435629· OSTI ID:7087072

Neynaber, R H; Magnuson, G D; Tang, S Y

Absolute and relative cross sections were obtained for the Penning-ionization (PI) reaction He*+He*..-->..He+He/sup +/+e and the associative-ionization (AI) reaction He*+He*..-->..He/sup +//sub 2/+e. The studies were made using a merging-beams technique for a relative kinetic energy W of the rectants from nominally 0.01 to 10 eV. The He* represents a composite of about 13% He(2 /sup 1/S) and 87% He(2 /sup 3/S). The He*--He* system is found to be attractive with a well depth of approximately 0.5 eV. The PI reaction is directed with most of the Penning ions scattered in the direction of the parent He*. The fraction of AI to total ionization (AI plus PI is only a few percent. Cross sections for total ionization vary as W/sup -0.38/ for W<0.1 eV. At W=0.033 eV our absolute total ionization cross section of 112 x 10/sup -/16 cm/sup 2/ agrees, within mutual errors, with the values obtained from most other experiments and from theory.

• Research Organization: IRT Corporation, San Diego, California 92138
• OSTI ID: 7087072
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 68:11; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular &amp; Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
ATOM-ATOM COLLISIONS
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
HELIUM
IONIZATION
METASTABLE STATES
NONMETALS
PENNING EFFECT
RARE GASES