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BibTeX file of [Sytcheva12a] [show it without abstract]

@article{Sytcheva12a,
    author={Arina Sytcheva and Stefan Pabst and Sang-Kil Son and Robin Santra},
    title={Enhanced nonlinear response of {Ne}^{8+} to intense ultrafast x rays},
    journal={Phys. Rev. A},
    volume={85},
    pages={023414},
    year={2012},
    keywords={Ne; x-ray; nonlinear; two-photon; cross section; TDCIS; XATOM; XCID; XFEL; CFEL; DESY;},
    url={https://doi.org/10.1103/PhysRevA.85.023414},
    doi={10.1103/PhysRevA.85.023414},
    abstract={We investigate the possible reasons for the discrepancy between the theoretical two-photon ionization cross section, $\sim$10$^{-56}$ cm$^4$s, of Ne$^{8+}$ obtained within the perturbative nonrelativistic framework for monochromatic light [S. Novikov and A. Hopersky, J. Phys. B \textbf{34}, 4857 (2001)] and the experimental value, 7$\times$10$^{-54}$ cm$^4$s, reported in [G. Doumy /textit{et al.}, Phys. Rev. Lett. \textbf{106}, 083002 (2011)] at a photon energy of 1110 eV. To this end, we consider Ne$^{8+}$ exposed to deterministic and chaotic ensembles of intense x-ray pulses. The time-dependent configuration-interaction singles (TDCIS) method is used to quantitatively describe nonlinear ionization of Ne$^{8+}$ induced by coherent intense ultrashort x-ray laser pulses. The impact of the bandwidth of a chaotic ensemble of x-ray pulses on the effective two-photon ionization cross section is studied within the lowest nonvanishing order of perturbation theory. We find that, at a bandwidth of 11 eV, the effective two-photon ionization cross section of Ne$^{8+}$ at a photon energy of 1110 eV amounts to 5$\times$10$^{-57}$ and 1.6$\times$10$^{-55}$ cm$^4$s for a deterministic ensemble and a chaotic ensemble, respectively. We show that the enhancement obtained for a chaotic ensemble of pulses originates from the presence of the one-photon 1$s$$^2$--1$s$4$p$ resonance located at 1127 eV. Using the TDCIS approach, we also show that, for currently available radiation intensities, two-photon ionization of a 1$s$ electron in neutral neon remains less probable than one-photon ionization of a valence electron.} }

Arina Sytcheva, Stefan Pabst, Sang-Kil Son, and Robin Santra, Enhanced nonlinear response of Ne8+ to intense ultrafast x rays, Phys. Rev. A 85, 023414 (2012) [pdf][pdf][abstract][abstract][link]doi:10.1103/PhysRevA.85.023414


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