Electronic and Structural Relaxation of Photoexcited WO 3 Observed by Femtosecond Resonant X-ray Emission Spectra

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High Resolution Image Download MS PowerPoint Slide Photoexcited states of tungsten trioxide (WO 3 ) were observed using femtosecond high-energy-resolution fluorescence detection X-ray Absorption Spectra (HERFD-XAS) and resonant X-ray emission spectra (RXES). In the initial state of the photoexcitation (∼100 fs), the W L 3 edge XAS shifts to lower energy and the energy levels of the t 2g and e g peaks are modulated due to the photoexcited electrons in the conduction band. The electronic state of the photoexcited W atoms is modified by 500 fs. The crystal field splitting between the t 2g and e g peaks shrinks by 500 fs, which indicates local structural changes around the W atoms due to the formation of polarons. HERFD-XAS and RXES provide more details about the early state of the photoexcited states of WO 3 . This work demonstrates that the detailed dynamics of 5d elements in the femtosecond range can be addressed with HERFD-XAS/RXES.

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