Femtosecond Optical Kerr Effect of Surface Modified PbS Nanocrystals

Surface modified PbS nanocrystals were fabricated by a novel method and their ultrafast optical nonlinearity was studied by the femtosecond time-resolved optical Kerr effect. A large nonlinear effect (x⁽³⁾~ 5 ×10^-12 esu) with a laser pulse limited response was observed. This may be attributed to the reduction of surface trapped electrons due to the surface modification.