Photon-Induced Diffusion in Thin Films and Single Crystals of Potassium Iodide

Thin films of potassium iodide have been prepared at both room and liquid nitrogen temperatures. Absorption spectra are presented which show that films deposited at liquid nitrogen temperature are quite disordered, but after warming to room temperature are very similar to those films deposited at room temperature. Evidence is given which shows that in thin films and also in single crystals of potassium iodide diffusion is promoted by the absorption of light. It is proposed that diffusion is caused by point thermal spikes at the absorbing centers.