Photoinduced hydrogen transfer reaction dynamics in indole–ammonia clusters at different excitation energies
Abstract
The dynamics of the H atom transfer reaction in indole·(NH3)n clusters has been studied in femtosecond pump–probe experiments as a function of the pump wavelength (250–282 nm), i.e. for different vibrational excess energies in the excited electronic states. Typical changes of the corresponding time constants in the sub-ps and ps time region were observed for the small clusters sizes (n = 1–3) and compared with those for the larger clusters (n = 4–6). For the heterodimer indole·(NH3)1 the energetic threshold of the reaction has been found at excitation energies of about 4.4 eV. In the sub-ps region we observed no isotope effect for all pump wavelengths used while on the ps time scale the rates for the deuterated clusters d-indole·(ND3)n are smaller by a factor up to 4 in comparison to the nondeuterated complexes.