Show simple item record

dc.creatorWine, P. H.en_US
dc.creatorGlick, R. E.en_US
dc.date.accessioned2006-06-15T13:42:10Z
dc.date.available2006-06-15T13:42:10Z
dc.date.issued1975en_US
dc.identifier1975-TH-02en_US
dc.identifier.urihttp://hdl.handle.net/1811/9503
dc.descriptionPresent address of P. H. Wine: Institute for Chemical Sciences, University of Texas at Dallas, Richardson, Texas, 75080.""en_US
dc.descriptionAuthor Institution: Department of Chemistry, Florida State Universityen_US
dc.description.abstractRelative apparent electron impact excitation cross sections have been determined for 27 levels of helium over a broad pressure range (0.02 - 0.91 Torr). Model calculations have been carried out where the data were fit to a set of coupled steady state equations which take into account primary and secondary electron excitation, radiative transfer, re-absorption of resonance radiation, and bimolecular and termolecular collisional processes. We find that collision Induced transitions of the type $n^{1}P \rightarrow n^{1}D$ are much more Important as populating mechanisms for $n^{1}D$ levels than had been previously believed and that the magnitude of the $4^{1}D$ apparent cross sections cannot be rationalised in terms of a model which assumes that transitions between all $(2L + 1) \times (2S + 1)$ sublevels are equally probable. A termolecular process, believed to involve formation of $He_{2}^{+}$, becomes an important loss mechanism for the longer lived n = 3 and 4 levels at pressures above 0.5 Torr. Rate constants for this process are estimated to be $(6.6 \pm 1.0) \times 10^{-27} cm^{6}$/sec and $(1.9 \pm 0.4) \times 10^{-27} cm^{6}$/sec for $3^{1}P$ and $4^{1}P$, respectively, the magnitude of the $3^{3}D$ and $4^{3}D$ apparent cross sections imply a large $4^{3}F$ population. This indicates that the 4F level is singlet-triplet mixed.en_US
dc.format.extent167026 bytes
dc.format.mimetypeimage/jpeg
dc.language.isoEnglishen_US
dc.publisherOhio State Universityen_US
dc.titleCOLLISIONAL TRANSFER OF EXCITATION IN HELIUMen_US
dc.typearticleen_US


Files in this item

Thumbnail

Items in Knowledge Bank are protected by copyright, with all rights reserved, unless otherwise indicated.

This item appears in the following Collection(s)

Show simple item record