Since 1990, advances in laser spectroscopy have made it possible to selectively excite and follow the fate of a single molecule with ultrafast resolution. This has made it possible to monitor the elementary processes that occur directly after absorption of a photon. This volume focuses on the conformational changes in organic molecules that result from absorption of a photon. These include those accompanying intramolecular excited state electron transfer, intra- and intramolecular excited state proton transfer, photoisomer formation, exciplex formation and control of photoproduct formation.