"This book analyses recent experimental data on the dissipation of energy injected into molecular systems by radiation, using the theory of radiationless transitions as the basis. Intramolecular vibrational redistribution and electronic relaxation in isolated molecules (including vibrational and electronic predissociation) as well as environment-induced effects (vibrational and rotational relaxation, collision-induced electronic relaxation) are considered as particular cases of general rules. Primary photochemical processes (isomerization, electron and proton or hydrogen-atom transfer) are treated in the same way. The sequential character of relaxation processes and the dependence of their rates on the energy (momentum) gap are emphasized. Only a basic knowledge of quantum mechanics and spectroscopy is required of the reader and calculations are reduced to a strict minimum, making the book accessible to students."--Jacket