Photochemistry of colloidal semiconductors 29. Fractionation of CdS sols of small particles by exclusion chromatography

CdS sols stabilized by sodium hexametaphosphate or poly-phosphate-15 were fractionated in a column of sephacryl gel and the fractions investigated by electron microscopy and spectrophotometrically. A linear relationship between the logarithm of the particle size and the elution time was observed. The method may be used to prepare sols of narrow size distribution and to analyse unknown samples with respect to the size of the particles. —The thermal growth of very small CdS particles was followed by chromatography. The particles grew rather abruptly from one size distribution to another, which may be explained by growth via particle combination.