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Title: Asymptotic behavior of apparent generalized oscillator strengths for optically forbidden transitions in rare-gas atoms

Abstract

Apparent generalized oscillator strengths (apparent GOS's) have been measured for three types of optically forbidden transitions in rare-gas atoms as functions of the squared momentum transfer K{sup 2} at small K{sup 2} range ({<=}0.4 a.u.). The apparent GOS's were deduced from the differential cross sections for excitation, which were measured by means of the electron energy-loss spectroscopy. Electron impact energies were 100, 300, and 500 eV, and the scattering angles were from 0.8 degree sign to 10 degree sign . In the case where the first Born approximation does not hold, the apparent GOS as a function of K{sup 2} (the apparent GOS function) shows characteristic dependence on the electron collision energy according to the character of the transition. In the present observation, for the np{sup 6} {sup 1}S{sub 0}{yields}np{sup 5}(n+1)p{sup '}[1/2]{sub 0} transitions, the specific behavior has been observed in the apparent GOS functions characteristic of that for the {sup 1}S{sub 0}{yields}{sup 1}S{sub 0} type transition, in which the term symbols of the initial and the final states do not change. For the np{sup 6} {sup 1}S{sub 0}{yields}np{sup 5}(n+1)p[5/2]{sub 2,3}; [3/2]{sub 1,2} transitions, a certain new type of deviations from the first Born approximation, which is interpreted to bemore » characteristic of the {sup 1}S{sub 0}{yields}{sup 1}D{sub 2} type transition, have been observed in the apparent GOS functions with some modifications depending on respective atomic species. For the 5p{sup 6} {sup 1}S{sub 0}{yields}5p{sup 5}5d [7/2]{sub 3}; [5/2]{sub 3} transitions in Xe, it is observed that the apparent GOS curves have no impact energy dependence for impact energies from 100 eV to 500 eV, which suggests that the first Born approximation is valid for such low impact energies and the curves agree with the Bethe-GOS. It is found that the GOS's varies in proportional to K{sup 4} at small K{sup 2} region ({<=}0.1 a.u.), which suggests that the octupole moment is dominant in these transitions. We interpret that these features of the behavior are specific for the {sup 1}S{sub 0}{yields}{sup 1}F{sub 3} type transition. On the whole, it is found that the behavior of the apparent GOS function can be well understood by considering the main contribution from a certain LS-coupling state when the excited state is represented by the intermediate coupling scheme which is expressed as a linear combination of the LS-coupled states.« less

Authors:
; ; ; ;  [1];  [2]
  1. Institute for Laser Science, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
20982325
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevA.75.032705; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ARGON; BORN APPROXIMATION; DIFFERENTIAL CROSS SECTIONS; ELECTRON-ATOM COLLISIONS; ELECTRONS; ENERGY DEPENDENCE; ENERGY-LOSS SPECTROSCOPY; EV RANGE 100-1000; EXCITATION; EXCITED STATES; FORBIDDEN TRANSITIONS; KRYPTON; L-S COUPLING; MOMENTUM TRANSFER; NEON; OSCILLATOR STRENGTHS; RARE GASES; SCATTERING; XENON

Citation Formats

Suzuki, T. Y., Suzuki, H., Ohtani, S., Takayanagi, T., Okada, K., and Department of Physic, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554. Asymptotic behavior of apparent generalized oscillator strengths for optically forbidden transitions in rare-gas atoms. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.032705.
Suzuki, T. Y., Suzuki, H., Ohtani, S., Takayanagi, T., Okada, K., & Department of Physic, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554. Asymptotic behavior of apparent generalized oscillator strengths for optically forbidden transitions in rare-gas atoms. United States. doi:10.1103/PHYSREVA.75.032705.
Suzuki, T. Y., Suzuki, H., Ohtani, S., Takayanagi, T., Okada, K., and Department of Physic, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554. Thu . "Asymptotic behavior of apparent generalized oscillator strengths for optically forbidden transitions in rare-gas atoms". United States. doi:10.1103/PHYSREVA.75.032705.
@article{osti_20982325,
title = {Asymptotic behavior of apparent generalized oscillator strengths for optically forbidden transitions in rare-gas atoms},
author = {Suzuki, T. Y. and Suzuki, H. and Ohtani, S. and Takayanagi, T. and Okada, K. and Department of Physic, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554},
abstractNote = {Apparent generalized oscillator strengths (apparent GOS's) have been measured for three types of optically forbidden transitions in rare-gas atoms as functions of the squared momentum transfer K{sup 2} at small K{sup 2} range ({<=}0.4 a.u.). The apparent GOS's were deduced from the differential cross sections for excitation, which were measured by means of the electron energy-loss spectroscopy. Electron impact energies were 100, 300, and 500 eV, and the scattering angles were from 0.8 degree sign to 10 degree sign . In the case where the first Born approximation does not hold, the apparent GOS as a function of K{sup 2} (the apparent GOS function) shows characteristic dependence on the electron collision energy according to the character of the transition. In the present observation, for the np{sup 6} {sup 1}S{sub 0}{yields}np{sup 5}(n+1)p{sup '}[1/2]{sub 0} transitions, the specific behavior has been observed in the apparent GOS functions characteristic of that for the {sup 1}S{sub 0}{yields}{sup 1}S{sub 0} type transition, in which the term symbols of the initial and the final states do not change. For the np{sup 6} {sup 1}S{sub 0}{yields}np{sup 5}(n+1)p[5/2]{sub 2,3}; [3/2]{sub 1,2} transitions, a certain new type of deviations from the first Born approximation, which is interpreted to be characteristic of the {sup 1}S{sub 0}{yields}{sup 1}D{sub 2} type transition, have been observed in the apparent GOS functions with some modifications depending on respective atomic species. For the 5p{sup 6} {sup 1}S{sub 0}{yields}5p{sup 5}5d [7/2]{sub 3}; [5/2]{sub 3} transitions in Xe, it is observed that the apparent GOS curves have no impact energy dependence for impact energies from 100 eV to 500 eV, which suggests that the first Born approximation is valid for such low impact energies and the curves agree with the Bethe-GOS. It is found that the GOS's varies in proportional to K{sup 4} at small K{sup 2} region ({<=}0.1 a.u.), which suggests that the octupole moment is dominant in these transitions. We interpret that these features of the behavior are specific for the {sup 1}S{sub 0}{yields}{sup 1}F{sub 3} type transition. On the whole, it is found that the behavior of the apparent GOS function can be well understood by considering the main contribution from a certain LS-coupling state when the excited state is represented by the intermediate coupling scheme which is expressed as a linear combination of the LS-coupled states.},
doi = {10.1103/PHYSREVA.75.032705},
journal = {Physical Review. A},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}