軟X線透過吸収法：分子間相互作用解析のための化学シフトと測定技術

摘要

Recent technical developments of X-ray absorption spectroscopy (XAS) enable us to measure in situ/operando transmission spectra of liquid samples in the soft X-ray region. We have discussed how various inter-molecular interactions around the core-excited atom are analyzed from the chemical shifts in XAS for the chemical state analysis of interacting molecular systems. We have newly developed liquid flow cells for XAS in transmission mode, where liquid samples are sandwiched between two100 nm thick Si_3N_4 (or SiC) membranes in vacuum or in helium atmosphere. In order to get reliable XAS spectra, our XAS system makes it possible to optimize the absorbance by simply controlling the liquid sample thickness from 20 nm to 2000 nm, and also makes it possible to find the region of uniform thickness by scanning the beam position on sandwiched liquid samples.%化学研究では，現実の複雑系を構成している成分を取り出 して，それぞれ理想的な均一状態にして解析する時代は過去 のものとなり，今は，これまで蓄積されてきた基礎情報に基 づき，現実の複雑系をそのまま扱う"その場観測"の時代に 入っている.また，複雑系の不均一な状態をそのまま観測す るにしても，全体の平均を見る時代から，局所的な相互作用 を区別して観測できる時代に移りつつある.