DYNAMICS OF EXCITED-STATES IN NI-2+-MGF2

Spectroscopic measurements on a single crystal of 0.2% Ni2+ :MgF2 reveal a new luminescence transition from the 1T2(1D) (Oh notation) excited state to the intermediate 3T1(3F) level. The 2.9 K luminescence consists of a series of sharp magnetic dipole (MD) origin transitions to the orthorhombic components of 3T1(3F) accompanied by vibronically induced electric dipole (ED) sidebands. It is shown that this new luminescence potentially provides a second channel for nonradiative excitation energy transfer by cross-relaxation in more concentrated crystals. Using an overall corrected luminescence spectrum spanning the range 6000-21000 cm-1, in combination with radiative decay measurements, the radiative and nonradiative decay rates of relaxation from 1T2(1D) are accurately determined. Pulsed laser excitation into 3T1(3F) reveals a 12 μs (2.9 K) rise for the 3T2(3F) → 3A2(3F) IR luminescence which corresponds to the lifetime of the 3T1(3F) level. © 1990.