大量の水中ナノドロップの水素結合水網に対するイオンの影響
Jeremy T O'Brien1, Evan R Williams
1Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
Journal of the American Chemical Society
|May 24, 2012
まとめ
様々なイオンを持つ水中ナノドロップを調査すると,イオン電荷が水分子の水素結合に影響することを明らかにします. 多価イオンは,ナノドロップの表面でも,水の構造を大幅に変化させます.
科学分野:
- 物理化学 物理化学
- スペクトロスコーピーは,スペクトロスコーピーを用います.
- マテリアルサイエンス 材料科学
背景:
- イオンと水の相互作用を理解することは,様々な化学的,生物学的プロセスにとって極めて重要です.
- ナノスケールの水滴の振る舞いは,散発水と大きく異なります.
- 顕微鏡法により,分子構造と結合に関する洞察が得られます.
研究 の 目的:
- ナノドロップの水分分子の水素結合ネットワークに異なるイオン (SO(4)(2-),I(-),Na(+),Ca(2+),La(3+)) の影響を調査する.
- ナノドロップ表面の水構造に対するイオン電荷とイオンタイプの影響を分析する.
- イオンによって引き起こされる構造の変化が表面に伝播する程度を決定する.
主な方法:
- 合体赤外線光解離 (IRPD) スペクトロスコーピーは,水性ナノドロップ (約250個の水分) の水素結合を検出するために使用されました.
- スペクトルは,水素の伸び領域 (~2800-3800cm(-1)) で133Kで記録されました.
- 分析は,表面水分子の結合されたおよび自由のヒドロキシル (OH) グループに対応する特徴に焦点を当てた.
主要な成果:
- Spectraは,結合されたグループと自由のOHグループの両方の特徴を示し,後者はAAD (AADは2つを受け入れ,1つの水素結合を寄付する) の水分子に起因しています.
- AADフリー-OH領域の周波数は,正イオン電荷が増加するにつれて赤にシフトし,スターク効果を示した.
- 単価イオンは水質結合ネットワークに最小限の影響を及ぼし,多価イオンはナノドロップ表面まで影響を及ぼし,水質結合ネットワークを大幅に変化させた.
結論:
- イオン電荷とイオンタイプは,ナノドロップの水の水素結合ネットワークに実証的に影響します.
- イオン誘発の電場によるスターク効果は,地表水分子の周波数に影響する.
- ナノドロップのイオン誘発による構造変化は,イオンから1nm以上離れた表面に広がります.
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