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Title: X-ray nonlinear optical processes using a self-amplified spontaneous emission free-electron laser

Journal Article · · Physical Review. A
;  [1]
  1. Argonne National Laboratory, Argonne, Illinois 60439 (United States)

In contrast to the long-wavelength regime, x-ray nonlinear optical processes are characterized in general by sequential single-photon single-electron interactions. Despite this fact, the sequential absorption of multiple x-ray photons depends on the statistical properties of the radiation field. Treating the x rays generated by a self-amplified spontaneous emission free-electron laser as fully chaotic, a quantum-mechanical analysis of inner-shell two-photon absorption is performed. It is demonstrated that double-core-hole formation via x-ray two-photon absorption is enhanced by chaotic photon statistics. Numerical calculations using rate equations illustrate the impact of field chaoticity on x-ray nonlinear ionization of helium and neon for photon energies near 1 keV. In the case of neon, processes are discussed that involve up to seven photons. Assuming an x-ray coherence time of 2.6 fs, double-core-hole formation in neon is found to be statistically enhanced by about 30% at an intensity of 10{sup 16} W/cm{sup 2}.

OSTI ID:
21020548
Journal Information:
Physical Review. A, Vol. 76, Issue 3; Other Information: DOI: 10.1103/PhysRevA.76.033416; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
Country of Publication:
United States
Language:
English