Abstract
The mechanisms of creation of a new combined electron-emissive state at 2.95 eV, 3.1 eV, 2.6–2.7 eV and 2.25–2.4 eV, which is a pre-decay state for energy transfer from the matrix to the emitters, were investigated in the CaSO4 −Bi phosphor. Combined electron-emissive states are formed from intrinsic SO43− − SO4− and impurity Bi2+ −SO4− electronhole trapping centers according to studying via spectroscopic and thermal activation methods. In turn, the intrinsic and impurity electron-hole trapping centers are created during excitation of the anionic complex SO42− as a result of charge transfer from the matrix to impurities (О2− −Bi3+ ) and neighboring anions (О2− − SO42− ). It is shown that the energy accumulated in the intrinsic matrix during external irradiation in the form of a combined electron radiative state of SO43− and Bi2+ decays as a result of the recombination process and is transferred to impurities.