Rapidly progressing photophysical and photochemical relaxation processes in complex organic molecules

Abstract

Using methods of high-speed kinetic laser spectroscopy, we investigated the dynamics and mechanisms of rapidly progressing relaxation processes in multiatomic molecules. We separated intra- and intermolecular channels of relaxation of the vibrational energy of excitation by the rate of transformation of nonstationary absorption spectra in a picosecond range of times. The role of highly excited electronic states in the process of electronic-vibrational relaxation in molecules of the class of phenazines was ascertained. Applying femtosecond light pulses in a real time scale, we recorded the dynamics of the decay of optically induced anisotropy in rarefied vapors of organic compounds. Several mechanisms of transfer of a hydrogen atom in the process of formation of free radicals in photoreduction of ketones were established. The dynamics of formation of inter- and intramolecular exciplexes in binary gas-phase systems was investigated. We determined the mechanisms of intramolecular dissociation of a C–O chemical bond in spiropyrans and xanthene dyes. Photodissociation of S–S bonds in molecules of disulfides was studied. The possibility of the existence of states with intramolecular charge transport with a twisted configuration for organic free radicals is shown.