Lifetime of helium metastable spin-states in a helium discharge

Date
1965
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract

The lifetime of a helium 23s1 metastable atom electronic spin-state is measured in helium gas using optical pumping techniques. The metastable atoms are created by an RF electrical discharge. The spin-state lifetime is found to vary with the -pressure of the helium and the intensity of the discharge. Also, the lifetime of the metastable atom is measured in the afterglow of a helium discharge. The metastable spin-state lifetime in a discharge is found to be much shorter than the metastable afterglow lifetime at the same pressure. At 1 mm Hg pressure, the afterglow lifetime of the metastable atom is about 1 as. At the same pressure in a discharge the metastable spin-state lifetime is found to be about 0.2 ms. The mechanism pro- posed to explain this difference is collisions of metastable atoms with the hot (~4 ev) electrons present in the dis-charge. The total cross-section for this process is large, and presumably a large fraction of the collisions will be effective in relaxing the spin-states.

Description
Degree
Master of Arts
Type
Thesis
Keywords
Citation

Byerly, Radford. "Lifetime of helium metastable spin-states in a helium discharge." (1965) Master’s Thesis, Rice University. https://hdl.handle.net/1911/89871.

Has part(s)
Forms part of
Published Version
Rights
Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.
Link to license
Citable link to this page