ANOMALOUS POPULATION DISTRIBUTIONS IN AN OPTICALLY EXCITED METASTABLE LEVEL IN CAF2 - TM2+

The population distribution among the magnetic sublevels of the metastable state of CaF2: Tm2+ is shown to be strongly influenced by spin orientation memory from the ground state. This memory is dependent on the wavelength and polarization of the pump radiation, being quite strong at 5790. The population is also influenced by an optical cross-relaxation or excitation transfer between neighboring ions, particularly so because the hyperfine splittings in the ground and excited states are almost identical. Also, it is shown that there is a high degree of nuclear spin orientation memory. © 1969 The American Physical Society.