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. 我们开发了一种新的装置，用于测量表面等离子体的激光共振激发，从一层聚合物或蛋白质，以及简单的分子吸附在金属薄膜上。该仪器使我们能够通过个人计算机在0.01‰的精度内自动改变入射角。反射率曲线也可以自动得到，并且可以很容易地在crt上绘制。用该装置观察了激光被水、甲醇、乙醇、十二烷基硫酸钠（SDS）和牛血清白蛋白（BSA）吸附在银薄膜上的反射率曲线。我们发现共振角随SDS和BSA浓度的变化曲线代表了吸附等温线。吸附在银薄膜上的SDS等温线表明，在衬底膜上存在两层SDS。根据上述理论，通过对反射率曲线的分析，估计层的宽度为36.9A^^。用水冲洗后，我们再次测量了共振角位移与浓度曲线，发现SDS单层紧密吸附在银膜上。非层的宽度为15A^^。在BSA的情况下，我们从共振角与浓度曲线观察到单层的存在，层的宽度估计为140A^^。已知BSA分子的形状为旋转椭球结构，其长轴长度为145A^^。由此可见，BSA分子位于底物上，其长轴与底物垂直。给出了激光反射率和表面等离子激元色散关系的新表达式。用这些公式对上述实验结果进行了分析。

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.