On the role of dissociative πσ* states in the photochemistry of protonated tryptamine and tryptophan:: An ab initio study

In very recent experiments, the excited-state lifetimes of protonated aromatic amino acids have been recorded by means of the pump-probe photodissociation technique. The excited-state decays are fast (picosecond time scale), leading to an extensive fragmentation of the protonated species. The calculations presented here for protonated tryptamine and tryptophan using a coupled-cluster method are meant to unravel the complex behavior of these systems. (c) 2005 Elsevier B.V. All rights reserved.