Ultrafast energy relaxation and trapping dynamics in semiconductor quantum dots

Summary form only given. We report femtosecond (fs) studies of energy relaxation and trapping dynamics in three types of quantum-dot systems: semiconductor nanocrystals (NC)/glass composites made by high temperature precipitation, ion-implanted NCs, and colloidal NCs generated via organometallic routes. Comparison of ultrafast data for these three types of samples allows us to separate effects intrinsic to quantum dots from those related to lattice imperfections and interface properties. High-sensitivity fs chirp-free transient absorption (TA) is applied to directly measure the population/depopulation dynamics.