Electron loss and deexcitation for fast, metastable helium atoms in gases

Journal Article · Sat Jan 01 04:00:00 EST 1977 · Phys. Rev., A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.15.53· OSTI ID:7323591

Pedersen, E H

Total cross sections in the energy range 25--450 keV for destruction of metastable helium atoms (i.e., electron loss and deexcitation) penetrating H/sub 2/, He, N/sub 2/, Ne, or Ar gas targets have been measured by the beam-attenuation technique. The fast, metastable helium atoms were formed by electron detachment from He/sup -/ ions in either a strong electric field or under single-collision conditions in H/sub 2/ or He gas. Apparent metastable fractions of the beams, which have also been extracted from the attenuation curves, depend strongly on the attenuation gas used. This shows that not only electron loss but also deexcitation is an important destruction mechanism for metastable helium atoms in these gases. The measured total destruction cross sections and apparent metastable fractions define upper as well as lower limits for both the electron loss and the deexcitation cross sections for metastable helium atoms. Generally, these limits lie close to each other. The experimental electron-loss cross sections for metastable helium atoms are in good agreement with semiempirical cross sections calculated in the classical impulse approximation of Bates and Walker. The experimental upper limit for the deexcitation cross section in a given gas is close to the electron-capture cross section for He/sup +/ in the same gas. (AIP)

• Research Organization: Institute of Physics, University of Aarhus, DK-8000 Aarhus C, Denmark
• OSTI ID: 7323591
• Journal Information: Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 15:1; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON
ATOM COLLISIONS
ATOM-ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
ATOMIC BEAMS
BEAMS
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
DE-EXCITATION
ELECTRON LOSS
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
HELIUM
HYDROGEN
KEV RANGE
KEV RANGE 10-100
KEV RANGE 100-1000
METASTABLE STATES
MOLECULE COLLISIONS
NEON
NITROGEN
NONMETALS
RARE GASES
TOTAL CROSS SECTIONS