Ikehata Akifumi, Goto Takeyoshi, Morisawa Yusuke
1 Food Research Institute, NARO, Ibaraki, Japan.
2 Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan.
Appl Spectrosc. 2017 Jul;71(7):1530-1536. doi: 10.1177/0003702817704171. Epub 2017 Apr 27.
Attenuated total reflection (ATR) spectra, which are often used in IR analysis, can be transformed into extinction and refraction spectra by Kramers-Kronig transformation (KKT) with Fresnel equations. However, it is often difficult to obtain correct optical indices due to the inherent instrumental functions. This paper proposes a simple practical method for correction of KKT with two parameters, which include all the effects of the instrumental function. In order to obtain the parameters of the instrumental function, absorption ratios of charge transfer to solvent (CTTS) transitions of aqueous iodide ions observed at 195 nm and 230 nm were used as a standard. The absorption indices calculated from the ATR spectra with the parameters correspond reasonably well to those given by the transmittance spectra not only in the UV region but also in the far-ultraviolet (FUV, 120-200 nm) region. By applying the corrected KKT to the ATR-FUV spectra of aqueous potassium halide solutions in the range of 0-2 M, correct features of the absorption spectra of KCl and KBr, whose CTTS bands are thought to be observed in FUV region, were confirmed. It is possible to use the parameters representing the instrument function as long as the instrument is not changed.
衰减全反射（ATR）光谱常用于红外分析，通过带有菲涅耳方程的克拉默斯-克勒尼希变换（KKT）可将其转换为消光光谱和折射光谱。然而，由于仪器固有的函数特性，往往难以获得正确的光学指数。本文提出了一种简单实用的双参数KKT校正方法，该方法涵盖了仪器函数的所有影响。为了获得仪器函数的参数，以在195nm和230nm处观测到的碘化水溶液中电荷转移至溶剂（CTTS）跃迁的吸收比作为标准。利用这些参数从ATR光谱计算出的吸收指数，不仅在紫外区域，而且在远紫外（FUV，120 - 200nm）区域，都与透过率光谱给出的值相当吻合。通过将校正后的KKT应用于0 - 2M范围内的卤化钾水溶液的ATR - FUV光谱，确认了氯化钾和溴化钾吸收光谱的正确特征，其CTTS带被认为在FUV区域观测到。只要仪器不变，就可以使用代表仪器函数的参数。
