Chemiluminescence during thermal degradation of sodium persulfate in the presence of terbium sulfate: 2. The effect of water of crystallization

An abnormally strong influence of water of crystallization on the intensity of chemiluminescence (CL) in the thermal degradation reaction of sodium persulfate in the presence of terbium(III) sulfate was revealed. As the water is driven off terbium sulfate Tb2(SO4)3 · nH2O (n= 8–0), the luminescence intensity and light sum increase. The maximum CL intensity for the completely dehydrated sample is 20 times higher and the light sum is two orders of magnitude greater than those of the crystal hydrate containing eight water molecules. It was found that the rise in the CL yield is due to an increase in the yield of excitation of the emitter *Tb(III), rather than the yield of its emission, with a change in the coordination environment.