Electron spin resonance in cadmium sulphide

Electron spin resonance measurements on sixteen undoped single crystals of CdS are reported. Three resonance lines have been observed which are not associated with impurities. Of the lines, which are designated as A, B and D, A and D are discussed in some detail. It is concluded that line D which has a g value near 1·8 is associated with the donor centre formed by a sulphur vacancy. It is suggested that line A is associated with a cluster of four nearest-neighbour cadmium vacancies which form an acceptor centre with a level approximately 0·7 ev above the valence band. The g value of line A varies slightly from sample to sample and is about 2·08.