Cathodoluminescence and laser-excited luminescence spectroscopy of Eu 3+ and Eu 2+ in synthetic CaF 2: a comparative study

Abstract

A comparative study of laser-excited luminescence and cathodoluminescence of CaF 2:0.1 % EuF 3 at room temperature was performed to determine the position and relative intensity of Eu 3+ and Eu 2+ main emission lines in CaF 2. Cathodoluminescence spectra show a major peak at 424 nm which is related to the electric dipole allowed 4f 65d-4f 7 transition of the Eu 2+ ion. The cathodoluminescence peaks of the Eu3+ ion are very weak and are not easily identifiable. Photoluminescence spectra recorded under different laser excitation conditions (corresponding to the 7F 0 →a- 5D 0 transition of the Eu 3+ ion) reveal major peaks around 590 nm due to the magnetic dipole allowed 7F 0 → 5D 1 transition of the Eu 3+ ion in three different environments: tetragonal, dimer and cubic. We emphasize the necessity of using a tunable laser to unambiguously identify the Eu 3+ ions in the minerals.