STUDY ON INTERFACE PHENOMENA BY OPTICAL WAVEGUIDE SPECTROSCOPY

利用平板光波导研制了可见光全内反射光谱测量系统。一种平板光波导，由作为导层的薄石英玻璃片（50 μ m厚）、作为包层的FEP膜和载玻片支撑体组成。用三甲基硅烷、丙基硅烷、辛基硅烷和十八烷基硅烷等硅烷化试剂，通过回流法或自组装法对石英玻璃表面进行化学改性。测量系统如下：使用微弧灯作为光源。光源光通过光纤和耦合棱镜（n_D=1.8785）引入SOWG。用另一个耦合棱镜取出输出光，偏振，然后引入使用CCD（Hamamatsu Photonics PMA-11，Japan）的多通道检测器。然后将信号发送到个人计算机，并连续获得时间分辨偏振可见TIR光谱（时间分辨率，0.2s）。在具有PTFE块的SOWG上构建流动池，并且用注射器手动引入染料水溶液。通过测量垂直引入的激光的吸收来监测样品溶液的引入。利用该体系研究了亚甲基蓝、罗丹明B和罗丹明6 G等染料分子在不同玻璃表面的吸附行为。例如，若丹明B的可见TIR光谱与若丹明B水溶液的吸收光谱几乎相同。也就是说，SOWG表面上的分子的单体与二聚体的比率与水溶液中的分子的单体与二聚体的比率相差不大。此外，偏振光谱的分析得到若丹明B分子（单体）的长轴与未改性玻璃的表面法线之间的平均角度为50度，对于甲硅烷基化玻璃为50至57度。

The measurement system for Visible total internal reflection (TIR) spectroscopy was developed using a slab optical waveguide (SOWG). A slab optical waveguide consists of a thin quartz glass sheet (50 mum thick) as a guide-layr, a FEP film as a clad and slide glass support. The surface of the quartz glass was chemically modified with various silylation reagents such as trimethylsilane, propylsilane, octylsilane and octadecylsilane by a reflux method or self-assembling method. The measurement system is as follows : a Xe arc lamp was used as a light source. The source light was introduced into the SOWG through an optical fiber and a coupling prism (n_D=1.8785). The output light was taken out with an another coupling prism, polarized, then led into a multichannel detector using a CCD (Hamamatsu Photonics PMA-11, Japan). The signals were then sent to a personal computer, and the time-resolved polarized Visible TIR spectra (time-resolution, 0.2s) were obtained continuously. A flow cell was built on the SOWG with PTFE block, and the aqueous dye solution was manually introduced with a syringe. The introduction of the sample solution was monitored by measuring an absorption of a perpendicularly introduced laser light. This system was applied to study the adsorption behavior of some dye molecules such as methylene blue, Rhodamine B and Rhodamine 6G onto various kinds of glass surface. For example, the Visible TIR spectrum of Rhodamine B is almost the same as the absorption spectrum of the Rhodamine B aqueous solution. That is, the ratio of the monomer of the molecule to the dimer on the SOWG surface is not much different from that in the aqueous solution. Moreover, the analysis of the polarized spectra yields an average angle of 50 degree between the long axis of the Rhodamine B molecule (monomer) and the surface normal for the not-modified glass, 50 to 57 degrees for silylated glasses.