Solvation Sphere of I- and Br- in Water

关键词: ABSORPTION;    ANIONS;    CONFIGURATION;    FINE STRUCTURE;    HALIDES;    SOLVATION;    WATER Other;   

DOI  :  10.2172/1017228
RP-ID  :  SLAC-TN-11-001
PID  :  OSTI ID: 1017228
Others  :  TRN: US201113%%702

学科分类：社会科学、人文和艺术（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

The solvation sphere of halides in water has been investigated using a combination of extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) analysis techniques. The results have indicated that I- and Br- both have an asymmetric, 8 water molecule primary solvation spheres. These spheres are identical, with the Br{sup -} sphere about .3 {angstrom} smaller than the I{sup -} sphere. This study utilized near-edge analysis to supplement EXAFS analysis which suffers from signal dampening/broadening due to thermal noise. This paper has reported on the solvation first sphere of I{sup -} and Br{sup -} in water. Using EXAFS and XANES analysis, strong models which describe the geometric configuration of water molecules coordinated to a central anion have been developed. The combination of these techniques has provided us with a more substantiated argument than relying solely on one or the other. An important finding of this study is that the size of the anion plays a smaller role than previously assumed in determining the number of coordinating water molecules Further experimental and theoretical investigation is required to understand why the size of the anion plays a minor role in determining the number of water molecules bound.