Electron correlation in two-photon double ionization of helium from attosecond to FEL pulses
- 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), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 956538
- Report Number(s):
- LA-UR-09-00375; LA-UR-09-375; TRN: US201014%%1907
- Journal Information:
- Journal of Physics B, Vol. 42, Issue 13
- Country of Publication:
- United States
- Language:
- English
Similar Records
Universal features in sequential and nonsequential two-photon double ionization of helium
Probing Electron Correlation via Attosecond xuv Pulses in the Two-Photon Double Ionization of Helium