Photochemistry of semiconductor colloids: Properties of extremely small particles of Cd3P2 and Zn3P2☆

Extremely small particles of Zn 3 P 2 and Cd 3 P 2 were prepared as colloids in aqueous solution and in the solid state. The onset of absorption and the fluorescence band, which lie in the infrared for the macrocrystalline materials, can be shifted through the whole range of the visible by changing the particle size. Fluorescence quantum yields of 15% were obtained. The optical effects are due to the strong perturbations in the electronic energy levels as a consequence of carrier confinement (Q-type materials). The solid particles, which fluoresce strongly, can be redissolved without changes in size. Methylviologen quenches the fluorescence and promotes the photoanodic dissolution.