Rapid and simple technique for the determination of the refractive index of ultra-thin organic films on planar transparent substrates using forward light scatter
Rapid and simple technique for the determination of the refractive index of ultra-thin organic films on planar transparent substrates using forward light scatter
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DOI：
10.1016/s0003-2670(00)01285-x
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发表时间：
2001-04-04
影响因子：
6.2
通讯作者：
Krull, UJ
中科院分区：
文献类型：
--
作者：
Henke, L;Piunno, PAE;Krull, UJ
我们开发了一种简单的技术，称为角度相关光散射(ADLS)，用于快速测定共价涂覆在光学透明衬底上的单层有机薄膜的折射率。ADLS涉及监测位于两个不同折射率的光学透明介质之间的界面上的准直光束的反射点正下方的光电探测器的响应作为入射角的函数。由于表面粗糙和缺陷引起的光散射，当入射角接近全内反射(TIR)的临界角时，在探测器响应中观察到局部极大值。根据经验，TIR的临界角可以从散射强度恢复到基线值的角度计算出来。在已知系统中另一种介质的折射率的情况下，这个由实验确定的临界角可以结合斯奈尔斯定律计算出薄膜的折射率为+/-0.05。通过对碳氢化合物(C-18硅烷)单层膜的研究和单链聚胸腺二酸单层膜(dT(20))与互补低聚物(da(20))的杂交反应的研究，证实了该技术的准确性。(C)2001 Elsevier Science B.V.保留所有权利。
A simple technique that we refer to as angularly dependent light scattering (ADLS) has been developed for the rapid determination of the refractive index of monolayer organic films that are covalently coated on optically transparent substrates. ADLS involves monitoring the response of a photodetector positioned directly below the point of reflection of a collimated beam of light at the interface between two optically transparent media of differing refractive index as a function of incident angle. A local maximum in the detector response is observed as the angle of incidence approaches the critical angle for total internal reflection (TIR) due to light scattering caused by surface roughness and imperfections. It has been empirically determined that the critical angle for TIR may be calculated from the angle at which the scatter intensity returns to baseline values. This experimentally determined critical angle may be used in conjunction with Snells' law to calculate the refractive index of a thin film to +/-0.05 if the refractive index of the other medium in the system is known. The accuracy of the technique has been confirmed by investigation of monolayer films of hydrocarbon (C-18 silane) and hybridization reactions of monolayer films of single-stranded polythymidilic acid (dT(20)) with complementary oligomer (dA(20)). (C) 2001 Elsevier Science B.V. All rights reserved.