Time‐resolved X‐ray reflection phases of the nearly forbidden Si(222) reflection under laser excitation. (12th April 2019)

• Record Type: Journal Article
• Authors: Tsai, Yi-Wei; Chang, Ying-Yi; Lee, Jey-Jau; Liu, Wen-Chung; Wu, Yu-Hsin; Liu, Wei-Rein; Liu, Hsing-Yu; Lee, Kun-Yuan; Weng, Shih-Chang; Sheu, Hwo-Shuenn; Chiu, Mau-Sen; Lee, Yin-Yu; Hsu, Chia-Hung; Chang, Shih-Lin
• Is Part Of: Journal of synchrotron radiation. Volume 26:Part 3(2019)
• Page Start: 819
• Page End: 824
• Publication Date: 2019-04-12
• Subjects: pump–probe experiments -- X‐ray reflection phases -- three‐wave diffraction -- laser excitation -- covalent electron density; Synchrotron radiation -- Periodicals; Free electron lasers -- Periodicals; 539.73505
• DOI: 10.1107/S1600577519003503
• Languages: English
• ISSNs: 0909-0495

Abstract

Abstract : Time‐resolved X‐ray reflection phases of the nearly forbidden Si(222) reflection under laser excitation are investigated using multiple‐wave diffraction at 7.82 keV. A relative phase change of around 4° of Si(222) in the first 100 ps of laser excitation and its gradual recovery over several nanoseconds are observed. Abstract : The covalent electron density, which makes Si(222) measurable, is subject to laser excitation. The three‐wave Si(222)/( ) 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.