Fig. 5.

Time-resolved SHG (dots) of the TiO₂ surface coated with 1.5 monolayers of EDT-treated 6.7 nm PbSe nanocrystals probed with p-polarized light with the electric field of the optical wave in the plane of incidence. The sample temperature was 12 K. Both pump and probe were 50 fs pulses of 810 nm light. The intensity of reflected second harmonic light at 405 nm was recorded as a function of time delay between the pump and probe pulses. The blue curve shows a least-squares fit incorporating electron injection and recombination (red) and three coherent phonon modes. Adapted from Tisdale et al., ref. 46.