液态水表面水合氢离子浓度增加的证据。

Evidence for an enhanced hydronium concentration at the liquid water surface.

作者信息

Petersen Poul B, Saykally Richard J

机构信息

Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.

出版信息

J Phys Chem B. 2005 Apr 28;109(16):7976-80. doi: 10.1021/jp044479j.

DOI:10.1021/jp044479j

PMID:16851932

Abstract

The recent demonstration of enhanced surface anion concentrations for aqueous electrolyte solutions strongly contrasts current textbook descriptions. Small cations are still expected to be repelled from the surface, but recent simulations predict that hydronium (H3O+) cations are instead preferentially adsorbed at the interface. Here we describe a comparative second harmonic generation (SHG) study of aqueous solutions of hydriodic acid (HI) and alkali iodides (NaI and KI), which establish lower limits of 55% and 34% larger surface iodide concentrations for HI solutions relative to NaI and KI solutions, respectively. This result implies that hydronium ions must exist in much higher densities near the liquid surface than do the alkali ions, in support of the theoretical predictions.

摘要

近期对水电解质溶液表面阴离子浓度增强的证明与当前教科书描述形成了强烈对比。小阳离子仍被认为会从表面被排斥，但最近的模拟预测水合氢离子（H3O+）阳离子反而优先吸附在界面处。在此，我们描述了一项对氢碘酸（HI）和碱金属碘化物（NaI和KI）水溶液的二次谐波产生（SHG）对比研究，该研究分别确定了HI溶液相对于NaI和KI溶液表面碘化物浓度下限分别高出55%和34%。这一结果意味着水合氢离子在液体表面附近的密度必须比碱金属离子高得多，这支持了理论预测。