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ピコ秒光アニソトロピーによって明らかにされたエタノールと水の混合物の構造的特徴

G S Beddard, T Doust, J Hudales

|February 17, 2018

まとめ

分子回転拡散は,エタノールと水の混合物におけるデビー・ストークス・アインシュタイン方程式から逸脱する. この研究は粘度だけでなく溶媒の組成が分子回転のリラックス時間に影響を及ぼすことを明らかにしています

科学分野:

フォト物理学
物理化学
分子力学

背景:

偏光による刺激は分子指向アニソトロピーを生み出します
分子回転運動はアニソトロピー崩壊と光脱極化を引き起こす.
水力学理論は通常,回転速度を予測する.

研究の目的:

分子回転拡散におけるデビー・ストークス・アインシュタイン (DSE) 方程式からの偏差を調査する.
ローテーションのリラックス時間に対する溶剤組成の影響を決定する.
エタノールと水の混合物の回転行動を分析する.

主な方法:

ピコ秒スペクトロスコーピー
染料のクレシル・バイオレットを探査機として使った
光脱極化測定を用いる.

主要な成果:

エタノールと水の混合物におけるクレシルバイオレットの DSE 行動から有意な偏差が観察された.
同じ粘度だが異なる組成の溶液で異なる回転リラクゼーション時間を特定した.
溶媒と溶液の相互作用が重要な役割を果たしていることを示した.

結論:

デビー・ストークス・アインシュタイン方程式は,すべての溶媒系における回転拡散を説明するのに不十分である.
溶媒の組成は分子の回転力学に大きな影響を与える.
水とエタノールの混合物について以前に提案されたモデルは,観察された行動を合理化することができます.

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