Connecting cluster anion properties to bulk: Ion solvation free energy trends with cluster size and the surface vs internal nature of iodide in water clusters
Connecting cluster anion properties to bulk: Ion solvation free energy trends with cluster size and the surface vs internal nature of iodide in water clusters
复制标题
DOI：
10.1021/jp962490g
复制
发表时间：
1997-03-13
影响因子：
2.9
通讯作者：
Coe, JV
中科院分区：
文献类型：
--
作者：
Coe, JV
关于小水团（最多类似于60个水）是否在表面、内部或在两个极端之间的状态中容纳过量的碘离子，文献中存在分歧。小簇溶剂化数据、中等大小的模型极性溶剂簇中的离子模拟结果以及大簇尺寸下的极限连续介质趋势相结合，说明了离子溶剂化自由能从最小簇尺寸到大块的进展，建立了一组簇离子溶剂化性质随簇尺寸的一般期望。在溶剂化热化学的簇离子性质、电子垂直脱离阈值和垂直脱离能的背景下，研究了水簇中碘化物的表面与内部状态问题，特别是关于簇大小和体积外推的变化。在水体系中，阴离子团簇垂直剥离阈值的性质比团簇垂直剥离能（峰中心）与阴离子缺陷光发射阈值的体性质具有更好的对应关系。结果表明，在碘化物水簇中，从小簇大小的表面状态到大簇大小的内部状态是一个渐进的过程，中间区域表现出中等程度的表面特征。在这方面，小的I-(H2O)(n)团簇与大的I-(ag)团簇不同，但可以对光剥离数据进行有意义的外推。
There is disagreement in the literature on whether small water clusters (up to similar to 60 waters) accommodate an excess iodide anion at the surface, in the interior, or in states intermediate between the two extremes. Small cluster solvation data, the results of ion simulations in model polar solvent clusters of intermediate size, and limiting continuum dielectric trends at large cluster size have been combined to illustrate the progression of the free energy of ion solvation from the smallest cluster size to bulk, establishing a set of general expectations for cluster ion solvation properties vs cluster size. The surface vs internal state issue for iodide in water clusters is examined in the context of the cluster ion properties of solvation thermochemistry, electron vertical detachment thresholds, and vertical detachment energies with specific regard to variation with cluster size and extrapolation to bulk. In aqueous systems, the anionic cluster property of vertical detachment threshold is shown to bear a better correspondence than the cluster vertical detachment energy (peak center) to the bulk property of the anionic defect photoemission threshold. It is concluded that in aqueous iodide clusters there is a gradual progression from surface states at small cluster size to internal states at large cluster size with the intervening region exhibiting an intermediate degree of surface character. Small I-(H2O)(n) clusters are unlike bulk I-(ag) in this regard, yet meaningful extrapolations of the photodetachment data to the bulk behavior can be made.