Multiple Sequential Ionization of Valence n = 4 Shell of Krypton by Intense Femtosecond XUV Pulses

Elena V Gryzlova,Maksim D Kiselev,Anton A Zubekhin,Giuseppe Sansone,Alexei N Grum-Grzhimailo,Maria M Popova

doi:10.3390/atoms8040080

Elena V Gryzlova, Maksim D Kiselev + Show 4 more

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https://doi.org/10.3390/atoms8040080

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Journal: Atoms	Publication Date: Nov 12, 2020
Citations: 3	License type: CC BY 4.0

Affiliation: Lomonosov Moscow State University, University of Freiburg

Abstract

Sequential photoionization of krypton by intense extreme ultraviolet femtosecond pulses is studied theoretically for the photon energies below the 3d excitation threshold. This regime with energetically forbidden Auger decay is characterized by special features, such as time scaling of the level population. The model is based on the solution of rate equations with photoionization cross sections of krypton in different charge and multiplet states determined using R-matrix calculations. Predictions of the ion yields and photoelectron spectra for various photon fluence are presented and discussed.

Highlights

Multiple ionization of atoms by intense pulses generated by free-electron laser (FEL) operating in the extreme ultraviolet (XUV) has been observed since the first experiments at the Free-electron
The ion yields of the different charge states are measured in the experiment as a function of the FEL pulse parameters and they are compared with the corresponding predictions of theoretical models [3,4]
Photoionization cross sections of multiplet states 4sk 4pm 2S+1 L for variously charged Kr ions were calculated by the B-spline R-matrix approach [44], which fully takes into account non-orthogonality of the electron functions before and after the ionization

Summary

Introduction

Multiple ionization of atoms by intense pulses generated by free-electron laser (FEL) operating in the extreme ultraviolet (XUV) has been observed since the first experiments at the Free-electron. LASer in Hamburg (FLASH) [1] Such studies are of great importance to benchmark theoretical models for the description of simple non-linear process in the XUV. Within a few femtoseconds the hole is filled by an electron originating from an outer shell, through a single or cascaded Auger decay mechanism. The ultrafast dynamics of the Auger decay competes with the absorption by the target ion of another photon from the same femtosecond FEL pulse. The ion yields of the different charge states are measured in the experiment as a function of the FEL pulse parameters and they are compared with the corresponding predictions of theoretical models [3,4]. Only a limited number of electronic spectra in this regime have been reported in the literature [2,5]

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