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Updated: Jan 30, 2026

Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating
Published on: October 11, 2016
Femtosecond phase-transition in hard x-ray excited bismuth
M Makita1, I Vartiainen2, I Mohacsi2,3
1Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland. mikako.makita@xfel.eu.
Abstract:
The 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.
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