Research

Photo-responsive materials are widely utilized in various industrial applications and in our daily lives, such as lithographic nanofabrication, 3D printers, photocatalysis, solar cells and so forth. We have been investigating the photo-responses of molecular systems, such as reactions in the electronically excited states and the relaxation processes from the nonequilibrium states, by means of the laser photolysis and time-resolved spectroscopy covering 10 fs (10-14 s) to several hours ranges. For the detection of the ultrafast molecular dynamics in very short time region, we use laser pulses with ultrashort temporal duration in femtosecond to picosecond time region. Dynamic behaviors following the pulsed laser excitation are detected also by ultrashort laser pulses, whose results provide detailed information on the mechanisms of molecular photo-responses. We have been applying these methods to the investigation on the fundamental photoreactions such as excitation energy transfer, photoinduced electron transfer, and chemical bond fission and creation, taking place in various molecular systems, e.g. natural photoactive proteins, artificial photoconductive systems, photochromic molecules, and so on. Control of the photochemical reactions by pulsed lasers is also an important project in our laboratory. By changing the excitation wavelength, pulse duration and by applying multiple excitation and multiphoton absorption, we are exploring the new molecular photo-responses leading to the novel photo-functions in the molecular systems, by collaborating with research groups of molecular synthesis and biological chemistry.