Subpicosecond Dynamic Hole-Burning of CdSe Nanoclusters

We report on a dynamic hole-burning study of 35-45angstroms CdSe nanoclusters in solution at 300K. The temporal evolution of the spectrum of the HOMO-LUMO exciton band after excitation with a 350 fs. pump pulse was recorded using a 350 fs. continuum pulse. A sharp feature is observed at short delays when the pump and probe overlap. This feature is a coherent coupling transient that effectively suppresses the large homogeneous broadening due to electronic dephasing. Longer delays show the full linewidth and probe the relaxation dynamics of the free exciton into trapped states.