[Electron spectroscopy and the electron structure of molecules]

The experimental-theoretical approach to the study of physico-chemical, in particular, spectroscopic and photochemical properties of groups of related molecules is considered. The problem of physically correct spectral decompositions of complex electronic spectra into bands corresponding to separate electronic transitions and of the information obtained therefrom is discussed. Concrete examples of revealing photo- and enzymatic reaction mechanisms by combined spectroscopic and theoretical studies of molecular electronic structure and spectra are given. Special attention is paid to the connection of electronic structure of molecules with their physico-chemical, in particular, spectroscopic properties.