Double and single ionization of He and H{sub 2} by slow protons and antiprotons
- Argonne National Lab., IL (United States)
- Riken, Inc., Wako, Saitama (Japan). Institute of Physical and Chemical Research
Double and single ionization of He and H{sub 2} by proton (p) and antiproton ({bar p})impact in the energy region below 50 keV was studied theoretically by using the semiclassical molecular picture. As the energy decreased, the ratio of the double- to the single-ionization cross section increased for impact and decreased for p impact for both He and H{sub 2}. These trends are consistent with recent measurements for He. Ionization mechanisms differ distinctly for p impact and {bar p} impact. For p impact, the dominant mechanism for double ionization at the lower energies is sequential ladder climbing by the two electrons through various excited channels and finally into the continuum. For {bar p} impact, in contrast, the approaching negative charge distorts both the He and H{sub 2} electron clouds toward the other side of the nucleus and decreases the electron binding energies. These effects enhance electron-electron interactions, increasing double ionization. For the H{sub 2}, an effect of molecular orientation is an additional complication in determining the dynamics.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 92093
- Report Number(s):
- ANL/ER/CP-85213; CONF-941268-3; ON: DE95005828; TRN: 95:018411
- Resource Relation:
- Conference: 4. U.S./Mexico joint symposium on atomic and molecular physics, San Juan Del Rio (Mexico), 7-10 Dec 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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