Spectral hole-burning in uranium-doped tungstates

Abstract

This paper describes the first observation of persistent spectral hole-burning in actinide-ion-doped crystals. Spectral hole-burning in three zero-phonon lines at 652.1 nm, 658.4 nm and 659.1 nm in SrWO4:U and one zero-phonon line at 654.4 nm in BaWO4:U is reported. The holes display quadratic Zeeman shifts. Also when the field is along the (110) direction the holes are split into two indicating the presence of two crystallographically equivalent sites of C2 symmetry. This is explained in terms of U6+ ions substituting for W6+ but having two equilibrium positions displaced in alternate directions along the c axis from the substitutional site. As well as narrow holes there are broad anti-holes, resulting in an unchanged integrated absorption that the hole-burning is photophysical. The mechanism is attributed to the reorientation of the U6+ between the two sites. Show more