Morita Shigeaki, Shinzawa Hideyuki, Noda Isao, Ozaki Yukihiro
Department of Chemistry, School of Science and Technology, Kwansei-Gakuin University, Sanda 669-1337, Japan.
Appl Spectrosc. 2006 Apr;60(4):398-406. doi: 10.1366/000370206776593690.
A new method of analysis, perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy, is proposed. For a spectral data set collected under an external perturbation, this method provides a pair of synchronous and asynchronous two-dimensional correlation spectra plotted on a plane between a spectral variable (e.g., wavenumber) axis and a perturbation variable (e.g., temperature) axis. One of the advantages of this new correlation analysis method is that complicated spectral variation along the perturbation direction can be monitored. It has been found that the synchronous and asynchronous PCMW2D correlation spectra are similar to the first perturbation derivative and negative second perturbation derivative spectra of the original data, respectively. To demonstrate the potential of PCMW2D correlation spectroscopy, it has been applied to temperature-dependent infrared (IR) spectra of a poly(vinyl alcohol) (PVA) film. The thermal behavior of the PVA film has been revealed by the PCMW2D correlation analysis. Two characteristic cross-peaks are observed in the synchronous PCMW2D correlation spectra generated from the temperature-dependent IR spectra between the crystalline phase C-O stretching band at 1141 cm-1 and the melting temperature of 209 degrees C and between the amorphous phase C-O stretching band at 1095 cm-1 and another specific temperature of 233 degrees C. This specific temperature of 233 degrees C corresponds to the thermal degradation temperature due to the elimination of the hydroxyl group attached to the main chain.
提出了一种新的分析方法——微扰相关移动窗口二维（PCMW2D）相关光谱法。对于在外部微扰下收集的光谱数据集，该方法提供了一对同步和异步二维相关光谱，绘制在光谱变量（如波数）轴和微扰变量（如温度）轴之间的平面上。这种新的相关分析方法的优点之一是可以监测沿微扰方向的复杂光谱变化。已经发现，同步和异步PCMW2D相关光谱分别类似于原始数据的一阶微扰导数光谱和负二阶微扰导数光谱。为了证明PCMW2D相关光谱法的潜力，已将其应用于聚乙烯醇（PVA）薄膜的温度相关红外（IR）光谱。通过PCMW2D相关分析揭示了PVA薄膜的热行为。在由温度相关红外光谱生成的同步PCMW2D相关光谱中，在1141 cm-1处的晶相C-O伸缩带与209℃的熔点之间以及在1095 cm-1处的非晶相C-O伸缩带与233℃的另一个特定温度之间观察到两个特征交叉峰。这个233℃的特定温度对应于由于主链上连接的羟基消除而导致的热降解温度。
