中国物理B ›› 2009, Vol. 18 ›› Issue (12): 5283-5290.doi: 10.1088/1674-1056/18/12/028

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Interference effects on the photoionization cross sections between two neighbouring atoms: nitrogen as an example

吴建华, 袁建民   

  1. Department of Physics, National University of Defense Technology, Changsha 410073, China
  • 收稿日期:2009-06-02 修回日期:2009-07-25 出版日期:2009-12-20 发布日期:2009-12-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 10734140), the National Basic Research Program of China (Grant No 2007CB815105).

Interference effects on the photoionization cross sections between two neighbouring atoms: nitrogen as an example

Wu Jian-Hua(吴建华) and Yuan Jian-Min(袁建民)†   

  1. Department of Physics, National University of Defense Technology, Changsha 410073, China
  • Received:2009-06-02 Revised:2009-07-25 Online:2009-12-20 Published:2009-12-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 10734140), the National Basic Research Program of China (Grant No 2007CB815105).

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摘要： Interference effects on the photoionization cross sections between two neighbouring atoms are considered based on the coherent scattering of the ionized electrons by the two nuclei when their separation is less than or comparable to the de Broglie wave length of the ionized electrons. As an example, the single atomic nitrogen ionization cross section and the total cross sections of two nitrogen atoms with coherently added photoionization amplitudes are calculated from the threshold to about 60~\AA (1~\AA=0.1~nm) of the photon energy. The photoionization cross sections of atomic nitrogen are obtained by using the close-coupling R-matrix method. In the calculation 19 states are included. The ionization energy of the atomic nitrogen and the photoionization cross sections agree well with the experimental results. Based on the R-matrix results of atomic nitrogen, the interference effects between two neighbouring nitrogen atoms are obtained. It is shown that the interference effects are considerable when electrons are ionized just above the threshold, even for the separations between the two atoms are larger than two times of the bond length of N2 molecules. Therefore, in hot and dense samples, effects caused by the coherent interference between the neighbours are expected to be observable for the total photoionization cross sections.

Abstract: Interference effects on the photoionization cross sections between two neighbouring atoms are considered based on the coherent scattering of the ionized electrons by the two nuclei when their separation is less than or comparable to the de Broglie wave length of the ionized electrons. As an example, the single atomic nitrogen ionization cross section and the total cross sections of two nitrogen atoms with coherently added photoionization amplitudes are calculated from the threshold to about 60 ? (1 ? = 0.1 nm) of the photon energy. The photoionization cross sections of atomic nitrogen are obtained by using the close-coupling R-matrix method. In the calculation 19 states are included. The ionization energy of the atomic nitrogen and the photoionization cross sections agree well with the experimental results. Based on the R-matrix results of atomic nitrogen, the interference effects between two neighbouring nitrogen atoms are obtained. It is shown that the interference effects are considerable when electrons are ionized just above the threshold, even for the separations between the two atoms are larger than two times of the bond length of N2 molecules. Therefore, in hot and dense samples, effects caused by the coherent interference between the neighbours are expected to be observable for the total photoionization cross sections.

Key words: interference effect, photoionization cross section, nitrogen atom

中图分类号:  (Photoionization of atoms and ions)

  • 32.80.Fb
31.15.-p (Calculations and mathematical techniques in atomic and molecular physics) 31.15.V- (Electron correlation calculations for atoms, ions and molecules)