Transient Coulomb Screening of Core Excitons in Wide Bandgap Semiconductors (Thomas Rossi) скачать в хорошем качестве

Transient Coulomb Screening of Core Excitons in Wide Bandgap Semiconductors (Thomas Rossi)

Title: Transient Coulomb Screening of Core Excitons in Wide Bandgap Semiconductors Speaker: Dr. Thomas Rossi (Helmholtz Center for Materials and Energy) Abstract: X-ray transient absorption (XTA) spectroscopy has emerged as a powerful tool for investigating the electronic and lattice dynamics of photoexcited materials on atomic length scales. This talk will showcase our recent progress in understanding excited-state XAS spectra of semiconductors on the picosecond timescale accessible at synchrotrons facilities. A key focus will be on the necessity of accurately subtracting lattice heating effects to isolate electronic contributions. I will report on case studies of photoexcited ZnO at the Zn K- and L-edge and NiO at the Ni K-edge, highlighting the sensitivity of XAS spectra to the dynamic screening of free carrier populations [1,2]. These results have implications for future XTA experiments at X-ray free electron lasers and for the operando study of optoelectronic materials. 1. Rossi, T. C. et al. Charge Carrier Screening in Photoexcited Epitaxial Semiconductor Nanorods Revealed by Transient X-ray Absorption Linear Dichroism. Nano Letters 21, 9534–9542 (2021). https://pubs.acs.org/doi/10.1021/acs.... 2. Rossi, T. C. et al. Ultrafast dynamic Coulomb screening of X-ray core excitons in photoexcited semiconductors. arXiv 110, 2412.01945v1 (2024). https://arxiv.org/abs/2412.01945