X線非弾性散乱による流体ダイナミクスの研究

Atomic dynamics in fluids studied by inelastic x-ray scattering

Inui Masanori

Kajihara Yukio

Matsuda Kazuhiro

Ishikawa Daisuke

Tsutsui Satoshi

Baron Alfred Q.

放射光

1990年代半ばにmeVオーダーのエネルギー分解能を達成したX線非弾性散乱実験技術により，高温高圧下の極端条件下にある超臨界流体の原子，分子ダイナミクス研究は大きく進展した。本稿では，著者らが独自の高温高圧実験技術を用いてSPring-8のBL35XUビームラインで行った，高温高圧下で膨張した流体水銀のX線非弾性散乱実験を中心に，液体，流体の原子ダイナミクスの理論的背景と，超臨界流体特有のダイナミクスについて紹介する。中でも，流体水銀の金属-非金属転移近傍で観察された，音響モードのエネルギーが超音波を用いて観測された音速よりも3倍大きい分散を示す速い音波の解明は，原子が凝集して金属が形成される素過程を理解する上で重要な現象と考えられる。本稿の結びでは，この分野の近い将来についても展望する。

Studies on atomic dynamics in supercritical fluids at high temperature and high pressure have remarkably been advanced by using an inelastic x-ray scattering technique that achieved a meV-energy resolution in the middle of 1990's. In this article, we describe a brief review of the theoretical background on liquid dynamics, our own high-temperature high-pressure technique and recent results of atomic dynamics in supercritical fluids. In particular, we report the results of inelastic x-ray scattering measurements for expanding fluid Hg at high temperature and high pressure, which were conducted at BL35XU/SPring-8. We found that in the metal-nonmetal transition in Fluid Hg, the excitation energy of the acoustic mode disperses three times faster than the adiabatic sound velocity obtained by ultrasonic measurements. This phenomenon must be crucial to understand how a metallic state is formed during atomic condensation accurately. Finally we put a future development of this field in perspective.

Physics [ 420 ]

jpn

日本放射光学会

Copyright (c) 2010 The Japanese Society for Synchrotron Radiation Research

[ISSN] 0914-9287

[NCID] AN10075706

[NAID] 10026552924