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Title: Generalized oscillator strengths for some higher valence-shell excitations of argon

Abstract

The valence shell excitations of argon were investigated by an angle-resolved fast-electron energy-loss spectrometer at an incident electron energy of 2500 eV, and the transition multipolarities for the excitations of 3p{yields}3d, 4d, 5s, and 5p were elucidated with the help of the calculated intermediate coupling coefficients using the COWAN code. The generalized oscillator strengths for the excitations to 3p{sup 5}(3d,3d{sup '}), 3p{sup 5}(5p,5p{sup '}), and 3p{sup 5}(5s,4d) were measured, and the profiles of these generalized oscillator strength were analyzed. Furthermore, although the present experimental positions of the maxima for the electric-monopole and electric-quadrupole excitations in 3p{yields}5p are in agreement with the theoretical calculations [Amusia et al., Phys. Rev. A 67, 022703 (2003)], the generalized oscillator strength profiles show obvious differences. In addition, the experimental generalized oscillator strength ratios for the electric-octupole transitions in 3p{yields}3d are different from the theoretical prediction calculated by the COWAN code.

Authors:
; ; ; ; ; ;  [1]
  1. Hefei National Laboratory for Physical Sciences at Microscale, Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)
Publication Date:
OSTI Identifier:
20982321
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevA.75.032701; (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; ELECTRIC CHARGES; ELECTRON-ATOM COLLISIONS; ELECTRONIC STRUCTURE; ELECTRONS; ENERGY LOSSES; ENERGY-LOSS SPECTROSCOPY; EXCITATION; FORECASTING; INTERMEDIATE COUPLING; KEV RANGE 01-10; OSCILLATOR STRENGTHS; QUADRUPOLES; SPECTROMETERS; VALENCE

Citation Formats

Zhu, Lin-Fan, Yuan, Hui, Jiang, Wei-Chun, Zhang, Fang-Xin, Yuan, Zhen-Sheng, Cheng, Hua-Dong, and Xu, Ke-Zun. Generalized oscillator strengths for some higher valence-shell excitations of argon. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.032701.
Zhu, Lin-Fan, Yuan, Hui, Jiang, Wei-Chun, Zhang, Fang-Xin, Yuan, Zhen-Sheng, Cheng, Hua-Dong, & Xu, Ke-Zun. Generalized oscillator strengths for some higher valence-shell excitations of argon. United States. doi:10.1103/PHYSREVA.75.032701.
Zhu, Lin-Fan, Yuan, Hui, Jiang, Wei-Chun, Zhang, Fang-Xin, Yuan, Zhen-Sheng, Cheng, Hua-Dong, and Xu, Ke-Zun. Thu . "Generalized oscillator strengths for some higher valence-shell excitations of argon". United States. doi:10.1103/PHYSREVA.75.032701.
@article{osti_20982321,
title = {Generalized oscillator strengths for some higher valence-shell excitations of argon},
author = {Zhu, Lin-Fan and Yuan, Hui and Jiang, Wei-Chun and Zhang, Fang-Xin and Yuan, Zhen-Sheng and Cheng, Hua-Dong and Xu, Ke-Zun},
abstractNote = {The valence shell excitations of argon were investigated by an angle-resolved fast-electron energy-loss spectrometer at an incident electron energy of 2500 eV, and the transition multipolarities for the excitations of 3p{yields}3d, 4d, 5s, and 5p were elucidated with the help of the calculated intermediate coupling coefficients using the COWAN code. The generalized oscillator strengths for the excitations to 3p{sup 5}(3d,3d{sup '}), 3p{sup 5}(5p,5p{sup '}), and 3p{sup 5}(5s,4d) were measured, and the profiles of these generalized oscillator strength were analyzed. Furthermore, although the present experimental positions of the maxima for the electric-monopole and electric-quadrupole excitations in 3p{yields}5p are in agreement with the theoretical calculations [Amusia et al., Phys. Rev. A 67, 022703 (2003)], the generalized oscillator strength profiles show obvious differences. In addition, the experimental generalized oscillator strength ratios for the electric-octupole transitions in 3p{yields}3d are different from the theoretical prediction calculated by the COWAN code.},
doi = {10.1103/PHYSREVA.75.032701},
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}
}
  • The generalized oscillator strengths for the valence-shell excitations to 3p{sup 5}(4s,4s{sup '}) and 3p{sup 5}(4p,4p{sup '}) of argon were measured by an angle-resolved fast-electron energy-loss spectrometer at an incident electron energy of 2500 eV. The transition multipolarities for these excitations were elucidated with the help of the calculated intermediate coupling coefficients using the COWAN code. The generalized oscillator strength profiles for the electric dipole excitations to 3p{sup 5}(4s,4s{sup '}), the electric quadrupole and monopole excitations to 3p{sup 5}(4p,4p{sup '}) were analyzed and their positions of the extrema were determined. Furthermore, the generalized oscillator strength of the electric quadrupole excitation inmore » 3p{yields}4p was determined and its profile is in general agreement with the theoretical calculations. However, the generalized oscillator strength profile of the electric monopole excitation in 3p{yields}4p is different from the theoretical calculations.« less
  • The generalized oscillator strengths for the valence-shell excitations to 2p{sup 5}3s, 2p{sup 5}3p, and 2p{sup 5}4s of neon were measured with an angle-resolved fast-electron energy-loss spectrometer at an incident electron energy of 2500 eV. The transition multipolarities for these excitations were elucidated with the help of the calculated intermediate-coupling coefficients using the COWAN code. The generalized oscillator strength profiles for the electric monopole, electric dipole, and electric quadrupole excitations were analyzed and their positions of the extrema were obtained. Furthermore, the experimental generalized oscillator strength ratios between the excitations to 2p{sup 5}4s[3/2]{sub 1} and 2p{sup 5}4s{sup '}[1/2]{sub 1} were determinedmore » and found to be in agreement with the calculated intermediate-coupling coefficient ratio.« less
  • The generalized oscillator strengths and differential cross sections for electron-impact excitation of the A{sup '} {sup 3}{Delta}{sub u}, Schumann-Runge continuum, and E {sup 3}{Sigma}{sub u}{sup -}({nu}{sup '}=0,1) states of oxygen have been determined at an incident electron energy of 2.5 keV. Good agreement is found between the present generalized oscillator strengths of the Schumann-Runge continuum and E {sup 3}{Sigma}{sub u}{sup -}({nu}{sup '}=1) states and the previous ones measured at higher impact energies, which indicates that the first Born approximation is satisfied at an impact energy of 400 eV. However, the large difference between the present generalized oscillator strengths of themore » A{sup '3}{Delta}{sub u} and E {sup 3}{Sigma}{sub u}{sup -}({nu}{sup '}=0) states and the previous ones is observed, and the possible reasons are discussed. The BE-scaled (binding energy B and excitation energy E) or BEf-scaled (B, E, and f values) integral cross sections for the A{sup '3}{Delta}{sub u}, Schumann-Runge continuum, and E {sup 3}{Sigma}{sub u}{sup -}({nu}{sup '}=0,1) states from its threshold to 5 keV were calculated based on the present generalized oscillator strengths. The present scaled integral cross sections are in good agreement with the previous ones measured at the moderate impact energies except for that of the A{sup '3}{Delta}{sub u} state.« less
  • A formula, which is a useful improvement over existing ones, has been obtained to calculate the generalized oscillator strengths (GOS's) for the discrete transitions of both open-shell and closed-shell atoms. We illustrate our formula by calculating the GOS for the oxygen 2p{sup 4}({sup 3}P)-2p{sup 3}({sup 4}S)3s({sup 3}S) transition and obtain overall good agreement with the experimental data. Our calculated GOS reveals a minimum at around the momentum transfer, K=1.26 a.u. We recommend a careful experimental search for the position of the minimum around the predicted value for confirmation.
  • The differential scattering cross sections and the generalized oscillator strengths of the 1{sup 1}{ital S}{r_arrow}2{sup 1}{ital S} and 1{sup 1}{ital S}{r_arrow}2{sup 1}{ital P} transitions of helium have been measured by angle-resolved electron-energy-loss spectroscopy with an incident electron energy of 1500 eV and within the range 2{degree}{endash}11.5{degree} of scattering angles. The corrections for angular factors and density effects have also been made for the experimental results. The differential cross sections and generalized oscillator strength values are absolute and are the first to be measured at such a high impact energy. The experimental results are compared with other measurements and theoretical calculationsmore » in the literature. {copyright} {ital 1996 The American Physical Society.}« less