Two-photon double ionization of helium: Evolution of the joint angular distribution with photon energy and two-electron energy sharing
- State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871 (China)
- Department of Physics and Astronomy, The University of Nebraska, Lincoln, Nebraska 68588-0299 (United States)
- Department of Engineering Science, University of Electro-Communications, 1-5-1 Chofu-ga-oka, Chofu-shi, Tokyo 182-8585 (Japan)
Ab initio calculations of two-photon double ionization of helium with photon energies varying from the nonsequential regime to well above the double-ionization threshold are presented. A systematic study of the joint angular distributions of the two ionized electrons at different energy sharing shows that the role of electron correlations is imprinted in the joint angular distribution. In particular, a rather general pattern is identified in the nonsequential regime that is independent of photon energy, pulse length, and energy sharing between the two electrons. Interestingly, the same distribution pattern is found for the equal-energy-sharing case, even when the photon energy is well above the double-ionization threshold. In the case of an extremely uneven energy sharing, the distribution pattern changes drastically as the photon energy is increased. In particular, when the photon energy is greater than the second-ionization threshold, the dominant emission mode of the two electrons switches gradually from ''back to back'' to ''side by side.'' Finally, the joint angular distribution is found to provide clear evidence of the role of electron correlations in the initial state.
- OSTI ID:
- 22095368
- Journal Information:
- Physical Review. A, Vol. 84, Issue 4; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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