Enhanced nonlinear double excitation of He in intense extreme ultraviolet laser fields.
Phys Rev Lett
; 107(24): 243003, 2011 Dec 09.
Article
em En
| MEDLINE
| ID: mdl-22242995
ABSTRACT
Nonlinear, three-photon double excitation of He in intense extreme ultraviolet free-electron laser fields (â¼24.1 eV, â¼5 TW/cm2) is presented. Resonances to the doubly excited states converging to the He+ N=3 level are revealed by the shot-by-shot photoelectron spectroscopy and identified by theoretical calculations based on the time-dependent Schrödinger equation for the two-electron atom under a laser field. It is shown that the three-photon double excitation is enhanced by intermediate Rydberg states below the first ionization threshold, giving a greater contribution to the photoionization yields than the two-photon process by more than 1 order of magnitude.
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Base de dados:
MEDLINE
Idioma:
En
Revista:
Phys Rev Lett
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Japão