Absolute cross sections for the dipole-allowed transitions 30{ital s}-30{ital p} and 29{ital d}-30{ital p} in collisions between charged particles and Na Rydberg atoms
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)
- State University of New York, Maritime College, 6 Pennyfield Avenue, Bronx, New York 10485 (United States)
Collisions between charged particles and highly excited Na Rydberg atoms have been measured to continue a study of the projectile-velocity dependence of collisionally induced dipole-allowed and dipole-forbidden transitions. Experiments involving H{sup +}, H{sub 2}{sup +}, He{sup +}, and Ne{sup +} projectiles incident on Na(30{ital s}) and Na(29{ital d}) cover the projectile-velocity range from 1.6 to 10 times the mean orbital velocity of the excited electron. The ratio of the sum of the two largest dipole-allowed cross sections that depopulate an initial 30{ital s} state (30{ital s}{r_arrow}30{ital p} and 30{ital s}{r_arrow}29{ital p}) to the total depopulation cross section of 30{ital s} has been measured for reduced velocities ranging from 5 to 10. {ital Absolute} cross sections for the two dipole-allowed transitions 30{ital s}{r_arrow}30{ital p} and 29{ital d}{r_arrow}30{ital p}, where large quantum defects play a significant role, are also presented. These exhibit characteristic velocity-dependent thresholds. The experimental data are in good agreement with close-coupling calculations that use an {ital m}-averaged dipole coupling to describe both allowed and forbidden channels. The results emphasize the importance of optically forbidden transitions and have implications in the study of astrophysical and laboratory plasmas.
- OSTI ID:
- 132899
- Journal Information:
- Physical Review A, Journal Name: Physical Review A Journal Issue: 5 Vol. 52; ISSN 1050-2947; ISSN PLRAAN
- Country of Publication:
- United States
- Language:
- English
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