Abstract: Using a modified solvothermal method in which potassium borohydride is employed as a reducing reagent,nanocrystal ZnSe materials are prepared in a triethylamine solvent.Compared to bulk ZnSe,nanocrystal ZnSe has a blue shift in its steady absorption edge.The degree of this blue shift increases with the decrease of nanocrystal particle size,as a result of quantum confinement effects.The ultrafast absorption spectra of ZnSe nanocrystals indicate that the electron-electron scattering time is 8.74ps and 2.77ps for the average nanocrystal size of 75 and 45nm,respectively.With the decrease of the size of nanocrystal,the probability of inelastic collision among carriers and nanocrystal surface increases,resulting in the enhancement of the carrier-phonon coupling strength and the shortening of the carrier-photon scattering time.

Key words: ZnSe nanocrystals, ultrafast absorption spectroscopy, carrier-phonon scattering