Determination of model-free Kramers-Kronig consistent optical constants of thin absorbing films from just one spectral measurement: Application to organic semiconductors
Determination of model-free Kramers-Kronig consistent optical constants of thin absorbing films from just one spectral measurement: Application to organic semiconductors
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DOI：
10.1103/physrevb.70.195432
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发表时间：
2004-11-01
影响因子：
3.7
通讯作者：
Fritz, T
中科院分区：
文献类型：
--
作者：
Nitsche, R;Fritz, T
我们提出了一种算法，它允许提取的折射率n和吸收系数k的薄吸收膜从一个光谱测量。该方法明确使用Kramers-Kronig关系互连n和k，从而产生一个先验的Kramers-Kronig一致的结果。不需要特定的模型来描述光学常数。该方法的成功应用证明，分析生成和实验记录的例子。由于吸收指数必须在测量边界处充分接近零的要求，我们将我们的方法的应用限制在表现出良好定义和不同吸收带的材料上。因此，差分反射光谱（DRS）的薄膜的有机半导体PTCDA（3，4，9，10-perylenetetracarboxylic dianhydride）在不同的基板透明云母，不透明的黄金和不透明的HOPG已被选为我们的实验例子。虽然我们特别关注我们的方法的应用，差分反射率测量，预计该方法可以同样适用于其他光学量。
We present an algorithm which allows to extract the refractive index n and the absorption index k of thin absorbing films from just one spectral measurement. The method makes explicit use of the Kramers-Kronig relation interconnecting n and k, thereby yielding an a priori Kramers-Kronig consistent result. No specific model is needed to describe the optical constants. The successful application of the method is demonstrated on both, analytically generated and experimentally recorded examples. Due to the requirement that the absorption index has to approach zero sufficiently at the measurement boundaries we restrict the application of our method to materials exhibiting well defined and distinct absorption bands. Consequently, differential reflectance spectra (DRS) of thin films of the organic semiconductor PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) on the different substrates transparent mica, opaque gold and opaque HOPG have been chosen as our experimental examples. While we especially focus on the application of our method to differential reflectance measurements, it is anticipated that the method can be applied to other optical quantities likewise.