Dissociative recombination of vibrationally excited H{sub 2}{sup +} ions: High-Rydberg-state formation

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Physical Review A

DOI:https://doi.org/10.1103/PhysRevA.56.443· OSTI ID:549300

Chibisov, M I ^[1]; Mitchell, J B; Van der Donk, P J ^[2]; Yousif, F B ^[3]; Morgan, T J ^[4]

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1. Russian Research Center, Kurchatov Institute, Kurchatov strasse 1, Institute of Nuclear Fusion, Moscow 123182 (Russia)
2. Department of Physics, University of Western Ontario, London, Ontario, N6A3K7 (CANADA)
3. Instituto de Fisica, UNAM, Cuernavaca, (Mexico) 62191
4. Physics Department, Wesleyan University, Middletown, Connecticut 06459-0155 (United States)

The dissociative recombination (DR) of vibrationally excited H{sub 2}{sup +} ions to form products in high Rydberg states has been investigated experimentally and theoretically for small (0.01{minus}0.1 eV) center-of-mass energies of the projectile electron. The merged beam method was used in the experiment and very large cross sections were found for DR from highly vibrationally excited states. The Rydberg states population was analyzed by the application of an electric field ionizer with an axial electric field in excess of 70 kV/cm, which is sufficient to ionize Rydberg states with n{ge}10. Experiments with and without the ionizer were performed and cross sections {sigma}(0{lt}n{le}21), {sigma}(n{lt}10), and {sigma}(10{le}n{le}21) were measured. The dipole approximation was used for the interpretation of the experimental results. Molecular rovibrational transitions were considered quantum mechanically. At low collision energy (0.01 eV), DR cross sections with high n=10{minus}21 Rydberg products arise from initial vibrational states v{ge}15. Absolute values of these cross sections are found to be of the order of magnitude of 10{sup {minus}12}{minus}10{sup {minus}13} cm{sup 2}. Comparison of theoretical and experimental results has shown that the modified back autoionization (involving transitions to the continuum and to very high n; that is the {open_quotes}indirect{close_quotes} mechanism of DR) plays a significant role for all cross sections. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 549300
• Journal Information: Physical Review A, Journal Name: Physical Review A Journal Issue: 1 Vol. 56; ISSN PLRAAN; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CATIONS
DISSOCIATION
ELECTRON-ION COLLISIONS
HYDROGEN IONS
HYDROGEN IONS 2 PLUS
RECOMBINATION
RYDBERG STATES
VIBRATIONAL STATES