Molecular photochemistry

Photochemistry is a very broad field that concerns the chemistry of excited states after a photon has been absorbed by the molecule. This contrasts with ground-state chemistry, which is typically performed by heating compounds. In this lecture, only the main principles are covered, starting with an introduction to the electronic and vibrational structure of molecules, the very important role of solvation, transition state theory, potential energy surfaces, Woodward-Hoffmann rules and Kenichi Fukui's frontier orbital theory to explain reaction products as a function of orbital symmetry and sign. These principles will be illustrated with examples from the photochemistry of olefins and alkenes. Finally, Marcus' theory of electron transfer reactions is explained and illustrated with experimental examples.