Direct observation of the electronic states of photoexcited hematite with ultrafast 2p3d X-ray absorption spectroscopy and resonant inelastic X-ray scattering

Ahmed S.M. Ismail, Yohei Uemura, Sang Han Park, Soonnam Kwon, Minseok Kim, Hebatalla Elnaggar, Federica Frati, Yasuhiro Niwa, Hiroki Wadati, Yasuyuki Hirata, Yujun Zhang, Kohei Yamagami, Susumu Yamamoto, Iwao Matsuda, Ufuk Halisdemir, Gertjan Koster, Bert M. Weckhuysen, Frank M.F. de Groot*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Hematite, α-Fe2O3, is an important semiconductor for photoelectrochemical water splitting. Its low charge carrier mobility and the presence of midgap states provide favourable conditions for electron-hole recombination, hence affecting the semiconductor's photoelectrochemical efficiency. The nature of the excited state and charge carrier transport in hematite is strongly debated. In order to further understand the fundamental properties of the hematite photoexcited state, we conducted femtosecond 2p (L3) X-ray absorption (XAS) and 2p3d resonant inelastic scattering (RIXS) measurements on hematite thin-films at the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL). The observed spectral changes and kinetic processes are in agreement with previous 3p XAS reports. The potential additional information that could be acquired from 2p3d RIXS experiments is also discussed.

Original languageEnglish
Pages (from-to)2685-2692
Number of pages8
JournalPhysical chemistry chemical physics
Volume22
Issue number5
DOIs
Publication statusPublished - 7 Feb 2020

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