Intensity-dependent near-threshold ionization of Kr in the vacuum-uv

Lazaros Varvarezos,Bastian Manschwetus,Alberto De Fanis,Mossy Kelly,Benjamin Erk,Michael Meyer,Gregor Hartmann,Cedric Bomme,Dimitrios Rompotis,Stefan Duesterer,Per Johnsson,Evgeny Savelyev,Andrey Kazansky,Tommaso Mazza,Nikolay Kabachnik,Costello John T

doi:10.1088/1742-6596/1289/1/012030

Abstract

In this work, we present measurements of the intensity-dependent photoelectron spectrum of Kr irradiated by the FLASH FEL tuned to a photon energy of 25.8 eV. Intensity dependent photoelectron spectra were obtained with the aid of a Velocity Map Imaging (VMI) spectrometer. As the FEL photon energy is close to threshold, two photon sequential double ionization is favoured. The number of open channels is kept to a minimum and leading to a simple description of the process.

Highlights

We present measurements of the intensity-dependent photoelectron spectrum of Kr irradiated by the FLASH free electron lasers (FELs) tuned to a photon energy of 25.8 eV
Observation of the two-photon double ionization of atoms in the VUV to soft X-Ray spectral region became possible with the advent of free electron lasers (FELs)[1]
Preliminary results In order to investigate the dependence of the several channels on the intensity, we divided the raw Velocity Map Imaging (VMI) images according to FEL pulse energy into 5 equal intervals ranging from the lowest 20 percent to the highest 20 percent

Summary

Introduction

Observation of the two-photon double ionization of atoms in the VUV to soft X-Ray spectral region became possible with the advent of free electron lasers (FELs)[1]. We present measurements of the intensity-dependent photoelectron spectrum of Kr irradiated by the FLASH FEL tuned to a photon energy of 25.8 eV. Intensity dependent photoelectron spectra were obtained with the aid of a Velocity Map Imaging (VMI) spectrometer. As the FEL photon energy is close to threshold, two photon sequential double ionization is favoured.

Results

Conclusion