The influence of surface modification on the femtosecond optical Kerr effect of PbS nanoparticles

PbS nanoparticles modified by cetyltrimethylammonium bromide (CTAB) and sodium dodecyl benzene sulphonate (DBS) have been synthesized. The subpicosecond optical nonlinearity of these PbS nanoparticles was investigated by using the femtosecond optical Kerr effect (OKE) experiment. The spectral behavior and the OKE results confirm that the surfactant environment has crucial rule on the linear and nonlinear optical properties. From the transient response, the relaxation time of the samples has been proved shorter than the laser pulse width.