Structure Analysis of Solution Surface by Photoelectron Yield XAFS Method.

X射线吸收精细结构(XAFS)谱是分析非晶态样品和液体近程结构的有力工具。本研究将其应用范围扩展到气/水界面的化学物种。尽管对溶液表面物种的溶剂化结构知之甚少，但分离在溶液表面的表面活性离子和分子在溶剂萃取、相转移和Langmuir-Blodgett膜的形成过程中起着重要作用。在全反射条件下，单色化X射线束以1mrad的掠入射角引入溶液池。电池包含一个66 mm x 216 mm的槽，冷却到1？A1C，该电池在大气压下充满了氦气。通过检测转换电子电流或氦离子电流来确定表面物种的XAFS。浓度为0.1 mM的硬脂酰三甲基溴化铵水溶液对BrK边吸收有较强的信号。透射法测得的光谱与本体溶液的光谱不同。

The X-ray absorption fine structure (XAFS) spectroscopy is a powerful tool for the short range structure analyzes of amorphous samples and liquids. In this study its application is extended to the chemical species at air/water interface. The surface active ions and molecules segregated at the solution surface are playing important role in the processes of solvent extraction, phase -transfer, and the formation of the Langmuir-Blodgett film, although almost nothing is known about the solvation structures of the surface species.The monochromatized X-ray beam was introduced into the solution cell at a grazing incidence angle of 1mrad under the total-reflection condition. The cell contains a 66mm x 216mm trough which is cooled to 1? A1C and the cell is filled with helium gas at an atmospheric pressure. The XAFS of the surface species was determined by detecting the conversion electron current or the helium ion current. Stearyltrimethylammonium bromide aqueous solution at 0.1mM concentration gave quite an intense signal for Br K-edge absorption. The spectrum was different from that of bulk solution by the transmission method.