An experimental study of state-selective electron capture by state-prepared low-energy (25 keV/amu) ions in atomic and molecular hydrogen
Abstract
The technique of double translational energy spectroscopy has been employed to study for the first time state selective electron capture by state-prepared doubly charged ions in atomic hydrogen. Highly dissociated hydrogen was provided by a microwave discharge source developed in this laboratory and energy change spectra for electron capture by ground (1S) and metastable (3P°) state C2+, ground state (2 P°) N2+ and ground state (3P) O 2+ in H have been obtained for collision energies ranging from 0.8 to 6 keV. For each collision system the main channels have been identified and their relative contributions measured. In the case of N2+ in H previously measured total cross sections could be used to determine the partial cross sections for capture into individual final states. The use of pure ground state and pure metastable state ion beams avoids the ambiguities inherent in previous translational energy spectroscopy studies where ion beams contained an undefined mixture of ground and metastable states. The results have been compared with previous experimental work and theoretical predictions where available. In particular the results for the C2+ +H system are in good agreement with the recent close-coupling calculations of Errea et al (2000). Energy change spectra were also obtained for electron capture in H 2. The distribution of final vibrational states of H2 + has been investigated and the most probable ν value determined.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 2000
- Bibcode:
- 2000PhDT........25V
- Keywords:
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- Physics: Atomic