Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA.
Phys Chem Chem Phys. 2010 Aug 1;12(29):8241-9. doi: 10.1039/c002299n. Epub 2010 May 24.
Beyond its fundamental interest, the acid dissociation of nitric acid (HNO(3)) at an aqueous interface is of importance in a wide variety of atmospheric contexts. Here we present a Car-Parrinello molecular dynamics (CPMD) study of the second step of this process, the formation, via proton transfer (PT), of a solvent-separated ion pair (SSIP) from a contact ion pair (CIP) of the hydronium (H(3)O(+)) and the nitrate (NO) ions. This reaction represents an extension of our earlier CPMD study of the first PT step to produce the CIP from molecular HNO(3) at various locations at and below the aqueous surface (S. Wang, R. Bianco and J. T. Hynes, J. Phys. Chem. A, 2009, 113, 1295); it is important in establishing the ionic distribution in the aqueous interfacial region, with potential consequences for heterogeneous reactions occurring in that region. We focus on the large amplitude, microscopic level motions-such as the hydrogen-bonding coordination number changes around the proton-donating and -accepting species-which are key for the CIP --> SSIP PT conversion.
除了其基本的兴趣之外，硝酸（HNO(3)）在水界面处的酸离解在各种大气环境中都非常重要。在这里，我们提出了一个 Car-Parrinello 分子动力学（CPMD）研究，研究了这个过程的第二步，即通过质子转移（PT），从水合氢离子（H(3)O(+)）和硝酸盐（NO）离子的接触离子对（CIP）形成溶剂分离离子对（SSIP）。该反应扩展了我们之前在不同位置和低于水表面的水相中，从分子 HNO(3)产生 CIP 的第一 PT 步骤的 CPMD 研究（S. Wang, R. Bianco 和 J. T. Hynes, J. Phys. Chem. A, 2009, 113, 1295）；它对于在该区域中发生的多相反应的离子分布建立非常重要，具有潜在的影响。我们关注的是大振幅、微观水平的运动，如质子供体和受体物种周围氢键配位数的变化，这些运动对于 CIP --> SSIP PT 转换是关键的。
