Is there a photochemical Hammond postulate?

The Hammond postulate is a useful tool for approximating the energy and the structure of transition states. It was designed for use in ground state reactions, and has been applied successfully on many occasions. On the other hand, its usefulness for photochemical reactions is more questionable, as different energy surfaces are involved. So far, no systematic studies on the validity of the Hammond postulate for photochemical reactions are available. The present work aims at filling this gap by providing a simple, unbiased series of test reactions based on the stereospecificity of isotopically labelled substrates.