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We report a detailed photoluminescence (PL) study on single silicon nanocrystals produced by laser pyrolysis. The PL spectra reveal nearly homogeneously broadened zero-phonon lines coupled to Si-O-Si phonon transitions in the SiO2 shell. A systematic investigation of electron-phonon coupling is reported on the basis of single nanocrystals. The stepwise localization of electron and hole at the Si-SiO2 interface for nanocrystals smaller than d approximately 2.7 nm is driven by electron-phonon coupling. From the localization energies the effective Bohr radii of the (localized) electron and hole are estimated to be in the range of 1-2 bond lengths of Si-O and Si-Si.

Fluorescent color-center patterns have been written on surfaces of synthetic type-Ib diamonds with spatial resolution below 180 nm via irradiation with focused ion and electron beams and subsequent annealing. The patterns are detected and spectroscopically analyzed using confocal optical microscopy. From the spatial extent of the color-center distributions, the activation energy for diffusion of vacancies in diamond is determined as (2.55±0.15) eV. Detailed information about the formation of color centers in diamond is obtained employing the three-dimensional spatial resolution of the confocal microscope combined with spectral resolution. In particular, the distributions of two color centers, ascribed to different charge states of the NV defect in diamond, have been spatially mapped and shown to depend strongly on the irradiation dose.