Influence of solvation on the indole photophysics: Ultrafast dynamics of indole–water clusters

The influence of water solvation on the photophysics of the indole chromophore has been investigated by revisiting the ultrafast relaxation of indole–water clusters. The dynamics after excitation in the 284–234 nm energy range has been tracked by time delayed ionization with a 1305 nm probe. The results collected in the indole– ( H 2 O ) 1 + mass channel, which were ascribed mainly to the indole– ( H 2 O ) 2 + cluster fragmented by dissociative ionization, reflect a dynamical behavior analogous to that observed for the isolated indole molecule. The two femtosecond time constants observed in the transients were assigned to the coupling between the L a and L b π π ∗ surfaces, and to the system evolution along the dissociative π σ ∗ state.