Nuclear quadrupole optical hole burning in stoichiometric EuAsO4

The intrinsic site and over forty defect sites have been studied by optical absorption, fluorescence and optical hole burning in EuAsO4. The hole-burning spectra have allowed determination of the nuclear electrical quadrupole parameters P and asymmetry parameters eta for the 5D0 levels for both Eu isotopes at 11 of these sites. A model is presented that explains the observed correlation between the P-values and the electronic energy shifts of the defect sites. Nuclear Zeeman effect studies of two sites using nuclear hole-burning spectroscopy in fields up to 8.8 T have allowed the determination of the orientation of their 5D0 electronic quadrupole tensors. Reasonable connection is made with two types of localised defect that are expected to occur frequently in the lattice structure. Energy transfer effects have also been examined as a function of temperature.