The initial photoinduced dynamics of thiomethyl p-coumaric acid (TMpCA) in solution has been studied with dispersed time-resolved pump-probe spectroscopy with a similar to100 fs instrument response and extending over a wavelength range of similar to300 to similar to600 nm. TMpCA is a model chromophore for the intrinsic chromophore found in photoactive yellow protein (PYP). Stimulated emission from the chromophore is quenched on a timescale similar to chromophore within the PYP protein. A product state absorption is also observed and is formed earlier than the relaxation of the excited state and that of an observed transient intermediate. (C) 2003 Elsevier Science B.V. All rights reserved.