Semiconductor doped glasses containing CdSxSe1-x nanocrystallites embedded in a silicate glass matrix were investigated. The dimensions of the nanocrystallites are in the range of a few nanometers and vary as a function of a secondary heat treatment. The confinement of such quantum dots for elementary excitations depends strongly on their size. In order to obtain a mean particle size and the size distribution, anomalous small angle x-ray scattering (ASAXS) and low-frequency inelastic Raman scattering measurements were performed. The sizes and the size distributions were evaluated for samples of different mean crystallite radius and composition x. The results of Raman measurements agree well with those of ASAXS, if both the acoustic mode damping across the nanocrystallite–matrix interface and the particle size distribution are taken into account in the Raman band shape analysis. The concentration of nanocrystallites in the glass matrix was determined by using the technique of contrast variation. Scattering curves were recorded at three energies below but close to the K-absorption edge of selenium (12.66 keV) and at 9.64 keV for comparison, which is significantly below the absorption edge. © 2000 American Institute of Physics.