Sensitive Monitoring of Surface Reactions with Optical Waveguide Dynamic Spectroscopy

1)应用光波导监测固体表面。我们有许多重要的反应发生在固体表面。固体表面的薄膜在工业上也越来越重要。结合这些，我们提出使用光波导（OWG）对固体和/或薄膜表面的化学反应进行灵敏检测（1988）。2)用于地面监测的OWG系统的开发，本项目采用了以下方法：2.1)在OWG中使用光的绝热跃迁。在导层较厚、衰减较小的OWG上覆盖具有高表面灵敏度的薄膜OWG。两个owg与锥形速度耦合器结合使用。作为典型的例子，我们在玻璃OWG上制备了FePO_4薄膜OWG。研究发现，锥度速度耦合器在第0模态需要0.5 mm长，在第1模态需要1 mm长才能实现完全绝热。利用该技术构建了OWG波段，测定了对表面物质的相对灵敏度(S)。S值约为10^3，是玻璃OWG的几十倍。2.2)OWG组件的新材料。以过氧化物多钨酸溶液为原料，采用旋涂法制备了薄膜，并对其基本光学特性进行了研究。它们的折射率为bbb2.0，对于在100^ C下固化的薄膜来说，折射率非常高。利用这些薄膜制备了薄膜OWGs、ARROW型OWGs和压纹光栅。此外，还详细研究了玻璃OWGs的基本特性，并基于WO_3的光致变色特性构建了化学传感器。

1) Applying optical waveguides to monitoring solid surfaces. We have many important reactions taking place at solid surfaces. Thin films on the solid surfaces are also increasing its importance in industry. In conjunction with these, we proposed a use of optical wave-guide (OWG) for sensitive detec tion on chemical reactions on the surfaced of the solids and/or the thin films (1988).2) Development of OWG systems for surface monitoring, The following approaches were made in this project.2.1) A use of adiabatic transition of light in OWGs. An OWG with a thick guiding layer, and hence with small attenuation, was covered with a thin film OWG having high surface sensitivity. The two OWGs were combined with taper velocity couplers. As a typical example, we made FePO_4 thin film OWG on a glass OWG. It was found that the taper velocity coupler needs to be 0.5 mm long for the 0th mode, and 1 mm for the 1st mode to realize totally adiabatic conditions. A band OWG was constructed by using this technique, and relative sensitivity (S) was measured for surface species. The S values were about 10^3, being several tens of times as large as that for glass OWGs.2.2) New materials for OWG components. Thin films of peroxopolytungstic acids were made from their solutions and with spin-coating, and basic optical characteristics were examined to make OWG components. Their refractive indices were >2.0, being very high for thin films cured at 100^ﾟC. Thin film OWGs, ARROW type OWGs, and embossed grating were prepared from these thin films. Moreover, basic characteristics of glass OWGs were examined in detail to construct chemical sensors based on photochromism of WO_3.