Time- and Space-Resolved Vibrational Spectroscopic Approaches to Elucidate the Behaviors of Complex Molecular Systems: From Biological Cells to Hybrid Solar-Cell Materials: ―細胞からハイブリッド太陽電池材料まで―

Elucidation of the behaviors of complex molecular systems is central to controlling their elaborate functions. It requires approaches that bear time and space specificities as well as chemical specificity, because various kinds of molecules act at different times and locations in order to carry out particular molecular processes. Timeand spaceresolved vibrational spectroscopies are a powerful method that can meet all of these requirements. This Account shows how these approaches enable us to investigate complex molecular systems including living cells, bacterial communities known as biofilms, and solar-cell materials. Raman microspectroscopy in combination with multivariate data analysis reveals dynamic changes in the concentrations and distributions of cellular components such as proteins and lipids, during the cell cycle without the need for labeling. It is also applied to study bacterial biofilms in a nondestructive manner with a focus on their metabolites (carotenoids in the present case). Nanosecond time-resolved IR spectroscopy is used to observe distinct transient species generated after photoexcitation in organic– inorganic hybrid perovskite solar cells, which are attracting tremendous interest of researchers as a promising next-generation photovoltaic device. The results presented here highlight that deciphering timeand space-resolved vibrational spectra has unraveled a number of new phenomena that are of relevance to biological/material functions.