The evolution of the optical phonon spectra of colloidal core/shell CdSe/ZnS quantum dots with an increase of the shell thickness from 0.5 to 3.4 monolayers has been studied by resonant Raman spectroscopy. The results obtained suggest that the ZnS shell changes its structure from amorphous to partly crystalline as the thickness increases. Simultaneously, an increase in Raman scattering by surface ͑core/shell interface͒ phonons and the redshift of the corresponding phonon band have been observed and assigned to variations in the shell structure. The disorder present in the shell provides a major contribution to the line shape of the Raman spectra at higher ZnS coverage. A method to control the quality of quantum dots based on Raman spectroscopy is proposed.

HIS REPORT is based on the histological ex-CANCER May 1953 Vol. G Fit;. I . Srniinonia. 'I'he large clcnt tiinior cells are divided into lobules by partitioning stroina rontaiiiing a inoderate ~iuinber ~l lytnphocytes. At the extrrnie right ati atrophic scniitiikrous tubule can lie seen. FIG. 2. Seminoma. The relative iiniforniity of the cells, the clear cytoplasm, and the cell borders are apparent at this power. Several mitoses are visible in this field. cally gonadal; the remainder resemble their counterparts elsewhere in the body. 454 CANCER May 1953Vol. 6

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