Some Se-related levels were studied by means of deep-level transient spectroscopy of the radioactive isotope, 75Se. Deep-level transient spectroscopic measurements were performed repeatedly during its transmutation to 75As. The 2 levels of the isolated Se atom were identified by their concentration decrease according to the radioactive decay law. The concentration of a level at Ec - 0.19eV decreased at twice the decay rate. This confirmed the involvement of two 75Se atoms. A Se-As pair, which formed an intermediate state in the Se2  (Se-As)  As2 transmutation, was discovered (Ec - 0.15eV).

N.Achtziger, W.Witthuhn: Physical Review Letters, 1995, 75[24], 4484-7