Ultrafast excited state dynamics of tri-branched derivatives based on 1,3,5-triazine: Pumped with different power conditions

Degenerate pump-probe experiment at wavelength of 400 nm, was performed to study the effect of the pump power condition on the excited state decay dynamics of tri-branched derivatives based on 1,3,5-triazine. These two styryl derivatives were dissolved in CHCl3 solutions, and different pump power densities were selected for the research in degenerated pump-probe measurement. Obvious different excited state decay dynamics were obtained under two conditions. When a relative low pump power density is chosen, the two tri-branched compounds show three processes: an ultrafast process approximately sub-ps (was ascribed to the coherent artifacts), a fast process approximately several ps (was ascribed to the formation of the intramolecular charge transfer state), and a long process approximately several hundreds of ps (was ascribed to the evolution of the intramolecular charge transfer state), respectively. When a high pump power density is employed, these processes were accelerated obviously, indicating some other processes of different mechanism involved.