Investigation of energy shift of 4f3 and 4f25d levels in Nd-doped YLF and LLF crystals 1 2

Abstract

We observed ultraviolet (UV) luminescence from 4f25d and 4f3 confi guration in Nd-doped YLiF4 (YLF) and LuLiF4 (LLF) crystals induced by multiphotonic excitation of the three photons (532 nanometers [nm]). The LLF lattice is more compact than the YLF crystal and favours an absorption and emission shift of the main peaks due to crystal fi eld strength. The red and blue shifts of the emission bands towards to lower (and higher) energy are different for the transitions from 4f3 and 4f25d levels. The 4f3 transitions have smaller shift (~5 times smaller than the shift of the 4f25d) due to 5s25p6 closed-shell shielding effect. On the other hand the 4f25d transitions are more susceptible to lattice change. The effect of the crystalline fi eld was compared for both lattice. The result shows that these emission bands from 4f25d confi guration always shift to lower energy when substituting the Y3+ by Lu3+ (i.e., the last one has the ionic radius 5% smaller than Y3+).