State-selective electron capture in (0.5{endash}50)-keV/u C{sup 5+}-He collisions studied by cold-target recoil-ion momentum spectroscopy
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)
Cross sections, differential in translational energy gain and projectile scattering angle, for single- and double-electron capture processes in collisions of C{sup 5+} ions with He at laboratory energies between 0.5 and 50 keV/u, have been studied experimentally by means of a high-resolution cold-target recoil-ion momentum spectroscopy. The translational energy spectra for single-electron capture show that capture into the C{sup 4+} (n=3) state is the dominant reaction channel observed over the entire collision energy region studied, in agreement with close-coupling calculations. However, capture into n=2 and n{ge}4 states is only significant at E{ge}4 keV/u. Transfer excitation processes contribute only very weakly to the total cross sections for single-electron capture (2{endash}4&hthinsp;{percent}). This contribution is considerably smaller than the close-coupling prediction. The autoionizing double-electron-capture (transfer ionization) spectrum clearly shows that C{sup 3+} (2l,2l{sup {prime}}) states are populated at the lowest impact energy, whereas contributions from capture into C{sup 3+} (2l,n{sup {prime}}l{sup {prime}}) states with n{sup {prime}}{ge}3 increase as the impact energy is increased and become the dominant process at E=35 keV/u. State-selective and differential cross sections have also been measured and compared with the close-coupling and multichannel Landau-Zener calculations. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 692507
- Journal Information:
- Physical Review A, Vol. 60, Issue 4; Other Information: PBD: Oct 1999
- Country of Publication:
- United States
- Language:
- English
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