Accession Number:

ADP019475

Title:

Total Ionization Cross Sections of Molecules by Electron Impact

Descriptive Note:

Conference paper

Corporate Author:

NATIONAL INST OF STANDARDS AND TECHNOLOGY GAITHERSBURG MD

Personal Author(s):

Report Date:

2004-04-01

Pagination or Media Count:

11.0

Abstract:

The theoretical basis for the binary-encounter-Bethe BEB model is outlined, and the model is compared to available experiments and other theories for samples of stable molecules, radicals, and positive ions. Possible directions for improving the BEB model also are presented. The BEB model does not contain empirical parameters, offers a simple equation and recipe for the ionization cross-section of individual molecular orbitals, and provides reliable cross-sections at low as well as high incident electron energies. The BEB model has been verified to produce reliable cross-sections for dozens of stable, neutral, large, and small molecules e.g., H2, SF6, radicals, and singly-charged positive ions. Section 2 discusses the theoretical basis for the BEB model. Section 3 compares BEB cross-sections with available experimental data for N2, CF4, SF6, CH3, N2 and SF5. It is clear that the BEB model can produce reliable ionization cross-sections for small as well as large, stable molecules. It also can produce reliable cross-sections for hydrocarbon radicals and singly-charged positive ions. However, the BEB cross sections do not agree well with the experimental data on radicals containing fluorine, CFx, SFx, and NFx, although the BEB cross-sections for the stable molecules CF4 and SF6 agree well with experiments. Section 4 examines unsolved issues and future prospects.

Subject Categories:

  • Inorganic Chemistry
  • Physical Chemistry
  • Atomic and Molecular Physics and Spectroscopy
  • Plasma Physics and Magnetohydrodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE