|
Read Full Article (file size: 399305 bytes) Cited by
JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
A04303,
doi:10.1029/2005JA011454,
2006
Analysis of electron impact ionization properties of methane
Xianming Liu
Planetary and Space Science Division, Space Environment Technologies, Pasadena, California, USA
Donald E. Shemansky
Planetary and Space Science Division, Space Environment Technologies, Pasadena, California, USA
Abstract
Published experimental photon and electron impact ionization cross sections of CH4 have been reviewed and analyzed. Absolute partial ionization oscillator strengths (f
ij
) for CH4
+, CH3
+, CH2
+, CH+, H+, and H2
+ have been obtained. Electron impact ionization cross sections are recommended based on agreement between the oscillator strength
values derived from photoionization and electron impact measurements. Analytic functions for cross sections of CH4
+, CH3
+, CH2
+, CH+, C+, H2
+, and H+ produced by electron impact ionization of CH4 are established. The derived excitation cross-section functions are accurate from threshold to impact energies limited by
relativistic effects (i.e., E < 0.2 MeV). The cross sections examined here are important for modeling Titan ionospheric chemistry.
Received 4
October
2005;
accepted 6
January
2006;
published 7
April
2006.
Keywords: electron-impact excitation function;
ionization oscillator strength;
methane ionization cross section.
Index Terms: 2423 Ionosphere: Ionization processes (7823); 2419 Ionosphere: Ion chemistry and composition (0335); 2447 Ionosphere: Modeling and forecasting; 7831 Space Plasma Physics: Laboratory studies and experimental techniques; 6280 Planetary Sciences: Solar System Objects: Saturnian satellites.
Read Full Article (file size: 399305 bytes) Cited by
Citation: Liu, X., and D. E. Shemansky
(2006),
Analysis of electron impact ionization properties of methane,
J. Geophys. Res.,
111,
A04303,
doi:10.1029/2005JA011454.
Copyright 2006 by the American Geophysical Union.
|