Dielectric spectroscopy of aqueous solutions of KCl and CsCl
Dielectric spectroscopy of aqueous solutions of KCl and CsCl
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DOI：
10.1021/jp026429p
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发表时间：
2003-05-22
影响因子：
2.9
通讯作者：
Buchner, R
中科院分区：
文献类型：
--
作者：
Chen, T;Hefter, G;Buchner, R
使用矢量网络分析仪（0.2小于或等于nu/GHz小于或等于20）和波导干涉仪（27小于或等于nu/GHz小于或等于89）测量，报告了KCl和CsCl水溶液在25 ℃下的介电弛豫研究结果。类似于以前报道的数据氯化钠，这两种盐的光谱拟合很好的科尔-科尔方程，虽然双德拜模型是竞争性的中间氯化铯浓度。溶质对水结构的影响，反映在体水弛豫时间随电解质浓度的增加而减少，顺序为NaCl > KCl > CsCl，并且似乎与阳离子的表面电荷密度成比例。K+和Cs+与水化壳层的相互作用很弱，不可能形成水分子的无旋键。有人认为，氯化铯表现出弱离子配对，虽然数据不够准确，以确定协会的程度和形成的离子对的性质。
Results of a dielectric relaxation study of the aqueous solutions of KCl and CsCl at 25 degreesC are reported using measurements with a vector network analyzer (0.2 less than or equal to nu/GHz less than or equal to 20) and with waveguide interferometers (27 less than or equal to nu/GHz less than or equal to 89). Similar to previously reported data for NaCl,, the spectra of both salts are well fitted by a Cole-Cole equation, although a double-Debye model is competitive at intermediate CsCl concentrations. The impact of the solute on the water structure, reflected in a decrease in the bulk-water relaxation time with rising electrolyte concentration, decreases in the sequence NaCl > KCl > CsCl and appears to be proportional to the surface-charge density of the cation. The interactions of K+ and Cs+ with their hydration shells are too weak to cause irrotational bonding of H2O molecules. It is argued that CsCl exhibits weak ion pairing, although the data are not sufficiently accurate to determine the extent of association and the nature of the ion pair formed.