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The controlled synthesis of PbSe nanocrystal quantum dots with narrow size distributions was achieved through phase decomposition of the PbSe solid solution in a phosphate glass host. Structural characterization by electron microscopy and x-ray diffraction shows that the dots have mean diameters between 2 and 15 nm. The exciton Bohr radius a B ϭ46 nm in PbSe, so these quantum dots provide unusual and perhaps unique access to the regime of strong quantum confinement. The optical absorption spectra are compared to the predictions of a theoretical treatment of the electronic structure. The theory agrees well with experiment for dots larger than ϳ7 nm, but for smaller dots there is some deviation from the theoretical predictions.

Soda lime glasses polarized either with an open or a blocking anode have been characterized by IR reflectance spectroscopy and a combined analysis of second harmonic generation and Raman imaging. The experimental results clearly show that the electrode nature influences strongly (i) the thickness of the space charge layer, (ii) the χ (2) efficiency, and (iii) the structural rearrangements. Besides, using theoretical models accounting for charge carriers' mobilities, the respective influence of two distinct compensation mechanisms, that is an injection of positive charges (H 3 O + /H + ions) or a drift of oxygen ions, have been confirmed.

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