Structure sensitive investigations on luminescence centres in Mn-activated LiBaF3 dosimeters

Prior to x-irradiation the photoluminescence (PL) of Mn-activated LiBaF3 shows a Mn2+Mn2+ emission band at 710 nm; the corresponding excitation bands are between 210 and 620 nm. After x-irradiation the PL emission spectrum shows a band peaking at about 610 nm which is tentatively assigned to a perturbed Mn2+Mn2+ emission; the intensity of all PL emission bands is increased. Structure sensitive investigations on the radiation-induced emission band were done by detecting electron paramagnetic resonance (EPR) induced changes in the integral PL emission at a temperature of 1.5 K. The analysis of the angular dependent PL-EPR spectra, recorded for different orientations of the magnetic field, yielded that the 610 nm luminescence band is due to an excited triplet state (S=1)(S=1) of a Mn-related centre with the zz-axis of the fine structure tensor close to a 〈110〉 direction.