Impact ionization in the proton--H-atom system. V. Final-cross-section calculations
The cross section sigma /sub I/( epsilon ;E) has been calculated for the direct impact-ionization of hydrogen atoms by protons, H/sup +/ + H(1s) yields 2H+ + e/sup -/, for low relative collision energies E between l00 and 500 eV, and all electron energies epsilon for which it is significant. Fundamental theory and most electronic matrix-element calculations were presented in earlier papers of the series. In the present paper we complete the electronic matrix- element calculations (in particular, thc -'optimization'' of Coriolis or angnlar coupling matrix elements for ionizing transitions, through introduction of an angular velocity electron-translation factor); and we perform the final integrations over classical trajectories and impact parameters to obtain the cross sections. The cross sections epsilon /I/( epsilon ; E) show the expected steep falloff with increasing epsilon and decreasing E, owing to the increasing inefficiency of momentum and energy transfer from the heavy particles to the electron under such changes; epsilon /sub I/ decreases by about two orders of magnitude from E = 500 eV to E = l.0 eV, and by four orders of magnitude from epsilon = 0 a.u. to epsilon = l.0 a.u. A strong dependence of cross section on isotopic mass at fixed E is also predicted thereby. Finally, the most significant conclusion is that the cross section for ionization from the 1s sigma /sub u/(2p sigma /sub u) molecular electronic state is about 500 times greater than that for ionizing a 1s sigma /sup g/ molecular electron, the main source of transitons being the Coriolis coupling operator. (auth)
- Research Organization:
- Division of Theoretical Chemistry, Department of Chemistry, The University of Alberta, Edmonton, Alberta, Canada T6G 2G2
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-013755
- OSTI ID:
- 4358664
- Journal Information:
- Phys. Rev., A, v. 8, no. 3, pp. 1316-1333, Other Information: Orig. Receipt Date: 30-JUN-74
- Country of Publication:
- United States
- Language:
- English
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