A systematic study of the ultrafast decay of metalloporphyrins containing various transition metals with partially filled 3d shells and zinc 3d filled is reported here after excitation in the second excited state of the system Soret band. Both time-of-flight mass spectrometry and velocity map imaging have been used for detection. A general biexponential decay with a short time constant 1100 fs is observed for the transition metal porphyrins, followed by a 21 ps time decay. This evolution is interpreted as a porphyrin-to-metal charge transfer, 1, followed by a back transfer, 2, which leads to an excited state d,d* localized on the metal. These conclusions stem from the different behaviors of zinc and the transition metal porphyrins. A porphyrin-to-metal charge transfer model is chosen to describe the relaxation mechanism, based upon the fact that transition metalloporphyrins can accept electrons on the metal site, in contrast to zinc porphyrins.
