Development of New Apparatus for Measurements of Resonant Excitation of Surface Plasmons by Laser from Layers of Polymers or Proteins Adsorbed on a Metal Thin Film

1.我们研制了一种新的测量装置，用于测量激光从一层聚合物或蛋白质以及吸附在金属薄膜上的简单分子中共振激发表面等离子体。该装置能在0.01 μ m的精度范围内用微机自动改变入射角。反射率曲线也自动获得，他们很容易绘制的CRT.用该装置观察了水、甲醇、乙醇、十二烷基硫酸钠（SDS）和牛血清白蛋白（BSA）吸附在银薄膜上的激光反射率曲线。我们发现，共振角位移与SDS和BSA浓度的曲线代表吸附等温线。SDS在银膜上的吸附等温线表明SDS在基底膜上存在两个吸附层。根据上述理论，通过对反射率曲线的分析，估算出吸附层的宽度为36.9埃。用水冲洗后，再次测定了SDS的共振角位移与浓度的关系曲线，发现SDS在银膜上存在紧密的单分子层吸附。非清除器的宽度为15埃。在BSA的情况下，我们从共振角-浓度曲线观察到单分子层的存在，估计吸附层的宽度为140埃。已知BSA分子的形状为旋转椭球体结构，其长轴长度为145 A ^^π。因此，我们认为BSA分子位于基底上，其长轴垂直于基底.推导了激光反射率和表面等离子体激元色散关系的新表达式。利用这些公式，我们分析了上述实验结果.

1. We have developed a new apparatus for the measurements of resonant excitation of surface plasmons by laser from a layer of polyners or proteins as well as simple molecules adsorbed on a metal thin film. This apparatus enables us to vary automatically incident angles by means of personal computer within the precision of 0.01ﾟ. Reflectivity curves are also obtained automatically and they are drawn readily an CRT.2. Using this apparatus we have observed the reflectivity curves of laser by water,methyl alcohol,ethyl alcohol,sodium dodecylsulfat(SDS), and bovine serum albusin(BSA) adsorbed on silver thin films. We have found that the curves of the shifts of resonance angles versus concentrations of SDS and BSA represent the adsorption isotherms. The isotherm of SDS adsorbed on silver thin film shows the existence of two adlayers of SDS stacked on the substrate film. The width of adlayers was estimated to be 36.9A^^ﾟ by the analysis of reflectivity curve on the basis of theory mentioned below. After the rinse of this adlayer by water we measured again resonance angle shift vs. concentration curves and found the existence of SDS monolayer tightly adsorbed on silver film. The width of the nonclayer was 15A^^ﾟ. In the case of BSA we observed the existence of monolayer from resonance angle vs. concentration curves and the width of adlayer was estimated to be 140A^^ﾟ. It is known that the shape of BSA molecule is rotatory ellipsoidal structure and the length of its major axis is 145A^^ﾟ. So we conclude that BSA molecules stand on the substrate and their major axes are vertical to the substrate.3. We have formulated new expressions for reflectivity of laser and dispersion relation of surface plasmon polariton. Using these formulas We have analyzed our experimental results described above.