若手のショートレビュー

レーザー衝撃圧縮下におけるベンゼンのナノ秒高速凝固反応:
時間分解コヒーレントアンチストークスラマン分光測定

Liquid-Solid Phase Transition of Benzene under Shock Compression
Studied by Time-Resolved Coherent Anti-Stokes Raman Spectroscopy

松田 晃孝
Akitaka MATSUDA

レーザー誘起衝撃圧縮下4.2 GPaにおけるベンゼンのナノ秒時間分解コヒーレントアンチストークスラマン分光測定を行った．衝撃圧縮下において高波数側にシフトした骨格伸縮振動モードおよびC-H伸縮振動モードに対応するピークの時間的遷移から，衝撃圧力を受けた直後の準安定な過圧縮液体を経由して25 ns以内に高速に固体状態へと転移していくことが明らかとなった．

Phase transition of benzene has been studied under laser-shock compression up to 4.2 GPa by using nanosecond time-resolved coherent anti-Stokes Raman spectroscopy. The shock wave is generated by irradiation of 10-ns pulsed laser beam on the plasma confinement target and its pressure is estimated form a particle velocity, which is measured by a velocity interferometer. The temporal evolution of the wavenumber shift of the ring-breathing mode and the C-H stretching mode is investigated. A metastable supercompressed state and a liquid-solid phase transition are observed under shock compression. Time-resolved Raman spectra reveal that the liquid state is initially preserved and rapidly transforms to the solid state within 25 ns under shock compression at 4.2 GPa.

Keywords: Phase Transition, Benzene, Shock Compression, Coherent Anti-Stokes Raman Scattering, Time-Resolved Spectroscopy