Ultrafast dynamics of CdSxSe1-x nanocrystals doped in glasses studied by ultrafast transient lensing effect

Ultrafast dynamics of CdSxSe1-x (x=0.26) nanocrystals doped in glasses was studied using a femtosecond ultrafast transient lensing (UTL) technique. Th ree kinds of samples with different average diameters (5.3 nm, 6.5 nm and 9 .4 nm, respectively) of CdSxSe1-x(x=0.26) nanocrystals were measured after photodarkened by irradiation of a pulsed laser light with a peak power dens ity of 3 GW/cm(2) for 2 minutes. The UTL signals showed tri-exponential beh aviors and three decay times were estimated to be about 1ps, 9 ps and > 300 ps. The three decay components were considered to be attributed to the dir ect recombination and trapping by some trapping states from the excited sta tes, and subsequently radiative and nonradiative recombination processes th rough two kinds of trapping states at the nanocrystal-glass interfaces for the photo-excited carriers. It was found that as the averaged size of CdSxS e1-x (x=0.26) nanocrystals in the glasses decreased, the relative intensity of the 3rd component increased while that of the 2nd component decreased.