Generalized two-dimensional correlation near-infrared spectroscopy and principal component analysis of the structures of methanol and ethanol

Liquid state methanol and ethanol under different temperatures have been investigated by FT-NIR (Fourier transform nearinfrared) spectroscopy, generalized two-dimensional (2D) correlation spectroscopy, and PCA (principal component analysis). First, the FT-NIR spectra were measured over a temperature range of 30–64 (or 30–71) °C, and then the 2D correlation spectra were computed. Combining near-infrared spectroscopy, generalized 2D correlation spectroscopy, and references, we analyzed the molecular structures (especially the hydrogen bond) of methanol and ethanol, and performed the NIR band assignments. The PCA method was employed to verify the results of the 2D analysis. This study will be helpful to the understanding of these reagents.