This award will facilitate cooperation in chemistry between Professor John H. Frederick of the University of Nevada, Reno, and the high resolution spectroscopy group headed by Professor Keitaro Yoshihara at the Institute for Molecular Science, Okazaki for a period of two years. The scientists will undertake a detailed study of the photoisomerization dynamics of stilbene and the spectroscopic analysis of cis-stilbene analogs. This system is a prototype for many naturally occurring photoisomerization reactions, including those associated with photosynthesis and vision. These processes typically involve large molecules with many electronic and nuclear degrees of freedom and are therefore very difficult to treat theoretically. To eliminate some of these difficulties, the scientists will employ a two-fold approach: (1) focusing only on a few of the low frequency vibrations that are pivotal in the isomerization reactions of cis-stilbene, and (2) first studying simpler systems that display activity in the same types of low frequency vibrations as cis-stilbene, but which do not undergo an isomerization reaction. The goal of this collaborative project, which involves the close interplay of experiment and theory, is to clarify the details of the fundamental isomerization process and add insight into the photochemical processes occurring in a variety of environments, including biological systems (vision and photosynthesis), surface coatings, and conductive polymers. The study of cis-trans isomerization is very important not only because this reaction is the most fundamental chemical reaction, but also because of its important role in photosynthesis (bacteriorhodospin) as well as in photoreception (vision, etc.).
