Nuclear quadrupole optical hole-burning in stoichiometric EuVO4

This study of EuVO4 is the first application of hole-burning techniques to the investigation of defect sites in a rare-earth compound. Laser excitation of the Eu3+ absorption spectrum in the region of the 7F0-5D0 forbidden transition (approx.=580 nm) reveals some 30 absorption lines. Each corresponds to a distinct crystallographic site in EuVO4, as there are no crystal-field splittings in a O-O transition. Hole-burning of several of these lines indicates a wide range of quadrupole splitting parameters P and eta, as would be expected for different crystallographic sites. More detailed study of two of these hole-burning spectra shows that, once the parameters P and eta are determined, Zeeman spectra of selected holes directly determine the orientation of the quadrupole tensor relative to the crystallographic axes. In such a simple crystal structure as EuVO4 it is not all obvious that there could be as many as 30 different types of defect site, and further studies will be needed to explain this. (author)