Measurements of metastable Argon atoms produced by electron impact
We have measured absolute level cross sections for electron excitation into the 1s{sub 3} and 1s{sub 5} metastable levels of Ar using a laser-induced fluorescence technique. The spin-forbidden nature of the direct excitation process allows us to calibrate absolutely our relative apparent excitation functions by matching them to our absolutely measured total cascade cross sections for electron energies above 90 eV. We find that the peak apparent cross sections for the 1s{sub 3} and 1s{sub 5} levels occur at about 22 eV and are 49 x 10{sup -19} cm{sup 2} and 30 x 10{sup -18} cm{sup 2} respectively. The direct cross sections peak at a few eV above the threshold and their maximum values are 14 x 10{sup -19} cm{sup 2} and 60 x 10{sup -19} cm{sup 2} for the 1s{sub 3} and 1s{sub 5} levels respectively. We have also shown applicability of the pulsed laser system for measuring absolute number densities and time-dependent measurements of these densities after the electron beam cutoff. The ratio of the 1s{sub 3} and 1s{sub 5} densities agrees very well with the ratio of our apparent cross sections.
- OSTI ID:
- 281265
- Report Number(s):
- CONF-9305421--
- Journal Information:
- Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 3 Vol. 38; ISSN BAPSA6; ISSN 0003-0503
- Country of Publication:
- United States
- Language:
- English
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