Ultrafast photoinduced processes in indole–water clusters

Applying femtosecond laser pulses at the wavelength of 250 nm the photoinduced processes in indole(H2O)n and d-indole(D2O)n clusters have been studied. An ultrafast (∼50 fs) decay of the initially excited ππ∗ state is tentatively attributed to the internal conversion to the dark πσ∗ state. Subsequent processes are characterized for n=1,2 by a single-exponential signal decay on the ps time scale, while for larger clusters (n⩾3) no significant time dependence is observed. The strong differences with respect to the photophysics of indole(NH3)n clusters are discussed.