femtosecond phase transition in hard x ray excited bismuth

• DOI: 10.48550/arxiv.1807.06865
• Publication Date: 2019-01-24
• Authors: Nikita Medvedev; Carl Caleman; Carl Caleman; Valerie Panneels; Vikrant Saxena; Christian David; Mikako Makita; Aldo Mozzanica; Paul Beaud; Pavle Juranić; Laura Vera; Ana Diaz; Sanghoon Song; Nadia Opara; Nadia Opara; Beata Ziaja-Motyka; Beata Ziaja-Motyka; Istvan Mohacsi; Istvan Mohacsi; Henrik Jonsson; Henrik Jonsson; Marcin Sikorski; Ismo Vartiainen; Philip R. Willmott; Christopher J. Milne; Alke Meents; Celestino Padeste
• Keywords: Fysikalisk kemi; femtsosecond phase-transition; Condensed Matter - Materials Science; info:eu-repo/classification/ddc/600; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; 600; hard x-ray excitation in bismuth single crystal; Condensed Matter Physics; Den kondenserade materiens fysik; Physical Chemistry; electron-ion equilibration process; Article

AbstractThe evolution of bismuth crystal structure upon excitation of its A1g phonon has been intensely studied with short pulse optical lasers. Here we present the first-time observation of a hard x-ray induced ultrafast phase transition in a bismuth single crystal at high intensities (~1014 W/cm2). The lattice evolution was followed using a recently demonstrated x-ray single-shot probing setup. The time evolution of the (111) Bragg peak intensity showed strong dependence on the excitation fluence. After exposure to a sufficiently intense x-ray pulse, the peak intensity dropped to zero within 300 fs, i.e. faster than one oscillation period of the A1g mode at room temperature. Our analysis indicates a nonthermal origin of a lattice disordering process, and excludes interpretations based on electron-ion equilibration process, or on thermodynamic heating process leading to plasma formation.