By use of differential absorption spectroscopy at different temperatures we investigate the homogeneous line broadening of small CdSxSelquantum dots embedded in glass. Our experiments show the strong correlation between the precipitation stages and characteristic optical parameters such as the saturation intensity and the longitudinal and transverse relaxation times. In samples grown in the diffusion-controlled regime to avoid coalescence, we find after strong laser excitation for the first time spectrally narrow holes in the non-linear differential absorption spectra. These sharp non-linear resonances with a halfwidth r of only 10 meV at T = 20 K allow us to investigate the energetic distance of the lowest hole levels and the temperature dependence of the line broadening. The different contributions of LO phonon coupling and temperature-independent scattering to the homogeneous linewidth will be analysed. The relaxation from the excited hole states has been investigated by exciting in the higher-energy hole states and measuring the resulting change in the ground state absorption.
Anomalous small‐angle X‐ray scattering (ASAXS) was employed to analyze CdSxSe1 −x‐doped silicate glasses, x = 0.4 and 0.6. From the intensity variations, as measured for four X‐ray energies near the K‐absorption edge of Se and at 9.5 keV, reliable values for the ratio of molecular densities in the crystalline CdSxSe1 −x phase and the surrounding amorphous matrix were found. Combination of this with the integrated intensity yields values for the CdSxSe1 −x volume fraction of 0.7 to 3%. Mean particle radii between 5 and 7 nm and number densities in the range 1 to 8 × 1016 cm−3 were obtained from fitted Gaussian and log‐normal size distributions, respectively.
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