Creation and Reaction of Solvated Electrons at and near the Surface of Water
Creation and Reaction of Solvated Electrons at and near the Surface of Water
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DOI：
10.1021/jacs.3c03370
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发表时间：
2023-05-16
影响因子：
15
通讯作者：
Nathanson, Gilbert M. M.
中科院分区：
文献类型：
--
作者：
Gao, Xiao-Fei;Hood, David J. J.;Nathanson, Gilbert M. M.
溶剂化电子(e（s)(-)）是自然界最强大的反应物之一，在散装水中研究了2600多种反应。这些电子也可以通过在真空中将水微射流暴露在气相钠原子中，在水的表面或附近产生，这些钠原子在最上面几层电离成e(s)（-）和Na+。当在射流中加入活性表面活性剂时，表面活性剂和e(s)（-）成为定域在界面区域的共反应物。我们报道了e(s)（-）与表面活性剂苄基三甲基铵在6.7 M的LiBr/water微射流中在235 K和ph = 2条件下的反应。反应中间体三甲胺（TMA）和苄基从溶液蒸发到气相后用质谱法鉴定。他们的检测表明，tmac1在质子化之前就能逃逸，在与自身或H原子结合之前就能苄基化。扩散反应计算表明，盐(s)（-）平均在距离表面20埃的范围内发生反应，可能在表面活性剂单层内发生反应，而未质子化的TMA从顶部40埃蒸发。反应较慢的苯自由基的逃逸深度超过1300埃。这些原理验证实验建立了一种通过将反应中间体蒸发到气相来探索水相体积相自由基化学的近界面类似物的方法。
Solvated electrons (e(s) (-))are amongnature's most powerful reactants, with over 2600 reactionsinvestigated in bulk water. These electrons can also be created atand near the surface of water by exposing an aqueous microjet in vacuumto gas-phase sodium atoms, which ionize into e(s) (-) and Na+ within the top few layers. When a reactive surfactantis added to the jet, the surfactant and e(s) (-) become coreactants localized in the interfacial region. We reportthe reaction of e(s) (-) with the surfactantbenzyltrimethylammonium in a 6.7 M LiBr/water microjet at 235 K andpH = 2. The reaction intermediates trimethylamine (TMA) and benzylradical are identified by mass spectrometry after they evaporate fromsolution into the gas phase. Their detection demonstrates that TMAcan escape before it is protonated and benzyl before it combines withitself or a H atom. Diffusion-reaction calculations indicate thate(s) (-) reacts on average within 20 angstrom of the surface and perhaps within the surfactant monolayer itself,while unprotonated TMA evaporates from the top 40 angstrom. The escapedepth exceeds 1300 angstrom for the more slowly reacting benzyl radical.These proof-of-principle experiments establish an approach for exploringthe near-interfacial analogues of aqueous bulk-phase radical chemistrythrough the evaporation of reaction intermediates into the gas phase.