Energy distributions of ions produced by electron-stimulated desorption

Stephen N. Schauer, Robert Thomas, Peter Williams

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

We have measured the initial kinetic energy distributions of ions produced by electron bombardment of various oxides and halides. The instrument used allows ions directly ejected from the sample surface to be distinguished from ions formed by electron impact in the gas phase. Singly and multiply charged positive ions of species present in the matrix as anions and cations were desorbed by high energy (∼ 11 keV) electron impact. Directly desorbed positive halogen ions show a narrow, low energy peak, consistent with conventional models of electron stimulated desorption (ESD). In addition, some of the cation species exhibited similar narrow energy spectra. Charge states up to +6 were observed for the halides; with the exception of F2+ and Cl2+, multiple charge states were due to electron impact ionization of desorbed neutrals. Charge states up to +4 were seen for silicon from electron-bombarded SiO2; energy distributions of Si+, Si2+ and Si3+ showed that these species were desorbed directly from the surface. The energy distributions of O+ and O2+ ions ejected from SiO2 are relatively wide, compared to the energy distribution of Si+ ions. In contrast, O+ ions ejected from TiO2 have a much narrower energy distribution, like those observed for the halogen ions.

Original languageEnglish (US)
Pages (from-to)277-285
Number of pages9
JournalSurface Science
Volume290
Issue number3
DOIs
StatePublished - Jun 20 1993

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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