Abstract
Infrared reflectance and excitation measurements, together with studies of the dependence of the luminescence on excitation intensity and sensitizer concentration, in the fluorides of La, Gd, and Y doped with and , , or indicate that infrared quantum counteraction is accomplished by absorption of energy in the ions followed by two (for or ) or three (for ) transfers to the activator, resulting in production of strong visible luminescence from absorption in the band. Saturation of the population of intermediate levels, in the case of -activated materials, was observed and is believed to account for previous results which were interpreted as evidence of a so-called "cooperative sensitization," in which only two (simultaneous) transfers were required.
- Received 5 December 1968
DOI:https://doi.org/10.1103/PhysRev.182.427
©1969 American Physical Society