| Abstract
| - We investigate the reaction between selenosulfate and (noncomplexed) Cd ions in aqueoussolution to form CdSe. The resulting precipitate, which is initially white (mainly CdSO3),turns yellow and finally orange. The initial precipitate is CdSO3, which gradually reactswith selenosulfate to give CdSe. The CdSe forms as a disordered phase surrounding theCdSO3, and this largely amorphous CdSe breaks off from the CdSO3 crystals to formnanocrystals of CdSe. The color changes during the reaction, due to size quantization of theCdSe nanocrystals, were correlated with the measured CdSe crystal sizes.
- High-resolution TEM micrograph of the yellow precipitate formed in the early stages of reaction between Cd2+ and selenosulfate. The upper left corner shows a relatively large CdSO3 crystal (formed at the start of the reaction from the free sulfite ions in the selenosulfate) reacting with selenosulfate to give CdSe at the surface. This CdSe separates from the CdSO3 surface as a (yellow) CdSe crystal of ca. 3 nm size.
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