Anoveltri-branchedcopolymerissynthesizedtoshowstrongtwo-photonabsorptionandintensetwo-photonabsorptioninducedfluorescenceemissionundertheexcitationofthefemtosecondlaserpulsesatwavelengthof80Ohm.Thedynamicsoftheexcitedstatewasmeasuredbythepump-probetechnique.Inaone-colourpump-probeexperimentat800nm,therewasanultrafasttransientabsorption,followedbyothertworelaxationprocesses.Thetwo-photonabsorptionprocesscouldbeoneoriginforthisultrafastphotoabsorptionsignal,whichwasfurtherprovenbytwo-colourpump-probeexperiments.Theothertwodecayingprocessesinthetransientabsorptiondynamicshavelifetimeofabout15psand129ps,whichreflecttheintrabandvibrationalrelaxationandthedecayoftwo-photonexcitedstate,respectively.
