Thermal effect of photolysis in 203Hg, 35S and 131I labeled mercury (II) iodide thiocyanate powders.

203Hg, 35S or 131I labeled mercury (II) iodide thiocyanate (HgISCN) powders were prepared, respectively. When the powders were exposed to sunlight, some parts of the crystals of the powders were decomposed and the decomposed atoms diffused toward crystal surface. This diffusion velocity was accelerated by thermal treatment of the darkened powders. The velocity is larger in order of 35S, 203Hg, 131I. Decomposed products consist of colloidal mercury, mercury iodide, mercury sulfide, sulfur dioxide and iodine. Mechanism of photochromism of HgISCN was discussed.