| Research Abstract |
The photoreaction of molecules depends largely on the nature of the excited state. It is interesting to study the relationship between the characteristics of the wave function of the excited state and the photoreaction, because such a study clarifies the effect of microscopic motion of electrons on the resultant photoreaction. The purpose of this project is to study the electronic-state dependence of photoreactions mainly by means of the emission spectroscopy. In order to perform this study, we made an emission spectrophotometer. We bought the spectrometer of the detection-side, the detector, and the controller. Previously, we had already bought the spectrometer of the excitation-side and the lamp. The sensitivity of the new spectrophotometer is much larger than the old one and the efficiency of the study was enhanced very much. We observed the fluorescence from the first and second excited singlet states of the related molecules of salicylaldehyde and discussed the electronic-state dependence of the proton transfer reaction. From theoretical studies, we found the effect of the node of the wave function on the photoreaction of organic molecules. Furthermore, we studied the proton transfer reactions in the triplet state and the ionic state of the related molecules of salicylaldehyde, the proton transfer in the lowest triplet states of 2-(2'-hydroxyphenyl)benzothiazole, 2-(2'-hydroxyphenyl)benzoxazole, and 2,2'-bipyridyl-3,3'-diol, the solvent effect on the relaxation processes of carotenoids showing dual emissive characteristics, the reason for the weak phosphorescence of pyridines. S. Nagaoka was chosen as 'Kagaku No Frontier VII' and 'the 6th Young Scholar Lecture' of the Chemical Society of Japan. He also wrote an invited paper in The Journal of Physical Chemistry published from the American Chemical Society (Vol. 95, pp. 10229-10235, 1991).
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