ON THE POSSIBILITY OF CHEMILUMINESCENCE ACCOMPANING THE Tb<sup>3+</sup> ION REDOX-REACTIONS INITIATED BY THE RADIOLYSIS OF AQUEOUS SOLUTIONS
The possibility of generating excited Tb3+ ion in reactions involving a hydrated electron (eaq-) and sulfate ion, initiated by radiolysis of terbium chloride aqueous solutions with (NH4)2SO4 additives is considered. From a comparison of the photo- and radioluminescence of these solutions, it was concluded that an increase in the Tb3+ luminescence intensity with an increase in the sulfate ion concentration in both cases is due to the formation of the inner-sphere complex [Tb3+(H2O)x(SO42-)y](3- y)+, which has a higher quantum yield of luminescence than the aquaion [Tb3+(H2O)x]3+. The chemiluminescence that is possible in the case of the solution radioirradiation during the reduction by eaq- of the Tb4+ ion formed as a result of the Tb3+ oxidation by the radiolytically generated radical ion SO4•- is not realized. An additional increase in the intensity of terbium radioluminescence is observed in the presence of eaq- selective acceptor, H+, in the solution, which is associated with the capture by the proton eaq-, which is an effective quencher of *Tb3+. This fact also excludes the existence of chemiluminescence Tb4+ + eaq- ® *Tb3+, otherwise the quenching of the radioluminescence of the terbium ion in the presence of H+ would be observed. It is concluded that the chemiluminescence mechanism of the Tb3+ ion luminescence during radiolysis is not realized, and the main source of its radioluminescence is the direct action of ionizing radiation on this ion.