Electron correlation in two-photon double ionization of helium from attosecond to FEL pulses

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Journal of Physics B

OSTI ID:956538

Collins, Lee ^[1]

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1. Los Alamos National Laboratory

We investigate the role of electron correlation in the two-photon double ionization of helium for ultrashort pulses in the extreme ultraviolet (XUV) regime with durations ranging from a hundred attoseconds to a few femtoseconds. We perform time-dependent ab initio calculations for pulses with mean frequencies in the so-called 'sequential' regime ({Dirac_h}{omega} > 54.4 eV). Electron correlation induced by the time correlation between emission events manifests itself in the angular distribution of the ejected electrons, which strongly depends on the energy sharing between them. We show that for ultrashort pulses two-photon double ionization probabilities scale non-uniformly with pulse duration depending on the energy sharing between the electrons. Most interestingly we find evidence for an interference between direct ('nonsequential') and indirect ('sequential') double photoionization with intermediate shake-up states, the strength of which is controlled by the pulse duration. This observation may provide a route towards measuring the pulse duration of x-ray free-electron laser (XFEL) pulses.

• Research Organization: Los Alamos National Laboratory (LANL)
• Sponsoring Organization: DOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 956538
• Report Number(s): LA-UR-09-00375; LA-UR-09-375
• Journal Information: Journal of Physics B, Journal Name: Journal of Physics B Journal Issue: 13 Vol. 42
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR DISTRIBUTION
CORRELATIONS
ELECTRON CORRELATION
ELECTRONS
EMISSION
ENERGY
EXTREME ULTRAVIOLET RADIATION
FREE ELECTRON LASERS
HELIUM
INTERFERENCE
IONIZATION
PHOTOIONIZATION
PULSES