Electron Impact Phenomena in VUV Photoionization Mass Spectroscopy
Abstract
Electron impact ionization arising from acceleration of stray electrons in the ion source is a major interference in photoionization mass spectrometry with vacuum ultraviolet sources. Results are presented which show that most of this ionization is caused by low energy secondaries generated when stray primaries are collected by the ion source electrodes. The primaries are produced mainly by interaction of scattered VUV radiation with metal surfaces. The low energy stray electron impact process can produce molecular ions as the only detectable electron impact features in the photoionization mass spectrum, especially for aromatic compounds. These features are not immediately distinguishable from photoions in the spectrum. When time of flight mass analysis is employed, the distinction can be made simply through adjustment of ion source conditions. The method for accomplishing this is described and demonstrated.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1987
- Accession Number
- ADA183365
Entities
People
- M. Bonner Denton
- Thomas C. Huth
Organizations
- University of Arizona