Ultrafast Optical Response from a Novel Tri-Branched Copolymer
LI Bo1,2, MI Jun1, MENG Fan-Shun3, TIAN He3, QIAN Shi-Xiong1
1Department of Physics, Fudan University, Shanghai 200433
2National Key Laboratory of Surface Science, Fudan University, Shanghai 200433
3Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237
Ultrafast Optical Response from a Novel Tri-Branched Copolymer
LI Bo1,2;MI Jun1;MENG Fan-Shun3;TIAN He3;QIAN Shi-Xiong1
1Department of Physics, Fudan University, Shanghai 200433
2National Key Laboratory of Surface Science, Fudan University, Shanghai 200433
3Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237
Abstract： A novel tri-branched copolymer is synthesized to show strong two-photon absorption and intense two-photon absorption induced fluorescence emission under the excitation of the femtosecond laser pulses at wavelength of 800nm. The dynamics of the excited state was measured by the pump-probe technique. In a one-colour pump-probe experiment at 800nm, there was an ultrafast transient absorption, followed by other two relaxation processes. The two-photon absorption process could be one origin for this ultrafast photoabsorption signal, which was further proven by two-colour pump--probe experiments. The other two decaying processes in the transient absorption dynamics have lifetime of about 15ps and 129ps, which reflect the intraband vibrational relaxation and the decay of two-photon excited state, respectively.
2004, Vol. 21 
