Time-resolved HAXPES using a microfocused XFEL beam: From vacuum space-charge effects to intrinsic charge-carrier recombination dynamics

Lars Philip Oloff, Ashish Chainani, Masaharu Matsunami, Kazutoshi Takahashi, Tadashi Togashi, Hitoshi Osawa, Kerstin Hanff, Arndt Quer, Ryuki Matsushita, Ryutaro Shiraishi, Maki Nagashima, Ayato Kimura, Kotaro Matsuishi, Makina Yabashi, Yoshihito Tanaka, Giorgio Rossi, Tetsuya Ishikawa, Kai Rossnagel, Masaki Oura

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Time-resolved hard X-ray photoelectron spectroscopy (trHAXPES) using microfocused X-ray free-electron laser (XFEL, hv= 8 keV) pulses as a probe and infrared laser pulses (hv=1.55 eV) as a pump is employed to determine intrinsic charge-carrier recombination dynamics in La:SrTiO3. By means of a combination of experiments and numerical N-body simulations, we first develop a simple approach to characterize and decrease XFEL-induced vacuum space-charge effects, which otherwise pose a serious limitation to spectroscopy experiments. We then show that, using an analytical mean-field model, vacuum space-charge effects can be counteracted by pump laser-induced photoholes at high excitation densities. This provides us a method to separate vacuum space-charge effects from the intrinsic charge-carrier recombination dynamics in the time domain. Our trHAXPES results thus open a route to studies of intrinsic charge-carrier dynamics on picosecond time scales with lateral spatial resolution on the micrometer scale.

Original languageEnglish
Article number35087
JournalScientific reports
Volume6
DOIs
Publication statusPublished - 2016 Oct 12

All Science Journal Classification (ASJC) codes

  • General

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