Spin-allowed and spin-forbidden fd emission from Er3+ and LiYF4

Physical Review B (Impact Factor: 3.66). 01/1998; 57(4). DOI: 10.1103/PhysRevB.57.R2025

ABSTRACT Luminescence measurements in the vacuum ultraviolet of 4f11-->4f10 5d transitions on Er3+ in LiYF4 have shown the presence of a weak fd band. The weakness of the band is explained by the spin-forbidden character of transitions from the ground state to this fd state, which is at lower energy than the spin-allowed fd bands. Upon excitation in the spin-allowed fd bands, both fast spin-allowed fd emission (tau=5 ns) and slow spin-forbidden fd emission (tau>2 mus) are observed. These results can be understood with a configurational coordinate diagram analogous to the Jablonski diagrams that are used to explain the fluorescence and phosphorescence from organic molecules.