Time-resolved X-ray reflection phases of the nearly forbidden Si(222) reflection under laser excitation

The covalent electron density, which makes Si(222) measurable, is subject to laser excitation. The three-wave Si(222)/(13 {\overline 1}) diffraction at 7.82   keV is used for phase measurements. It is found that laser excitation causes a relative phase change of around 4 ° in Si(222) in the first 100   ps of excitation and this is gradually recovered over several nanoseconds. This phase change is due to laser excitation of covalent electrons around the silicon atoms in the unit cell and makes the electron density deviate further from the centrosymmetric distribution.

Source: Journal of Synchrotron Radiation - April 11, 2019 Category: Physics Authors: Tsai, Y.-W. Chang, Y.-Y. Lee, J.-J. Liu, W.-C. Wu, Y.-H. Liu, W.-R. Liu, H.-Y. Lee, K.-Y. Weng, S.-C. Sheu, H.-S. Chiu, M.-S. Lee, Y.-Y. Hsu, C.-H. Chang, S.-L. Tags: pump – probe experiments X-ray reflection phases three-wave diffraction laser excitation covalent electron density research papers Source Type: research