GAIN PROCESSES IN CDSE QUANTUM DOTS

The bleaching of the absorption has been studied for CdSe quantum dots in the strong confinement limit by nanosecond pump-and-probe spectros copy. For high excitation we detect optical gain in a broad spectral r egion below the absorption edge accompanied by a new peak in the lumin escence. The gain arises from stimulated decay of inverted one-electro n-hole pair states and of two-electron-hole pair states. These results are confirmed by examination of the time-resolved luminescence.