Analysis of Energy Transfer and Infrared‐to‐Visible Conversion in LaF3:Yb, Er

摘要

A model of the energy transfer between Yb3+ and Er3+ in LaF3 which explains the efficiency and time dependence of the conversion of infrared excitation to visible emission in this material is presented and analyzed. It is concluded that in La0.86Yb0.12Er0.02F3 the probability of an excited Yb3+ ion transfering its energy of excitation to an Er3+ ion is at least an order‐of‐magnitude greater than the probability of the Yb3+ ion decaying with the emission of radiation or phonons. Similarly, an Er3+ excited to its 4I11/2 state is much more likely to lose the energy of excitation by radiationless energy transfer to a Yb3+ ion than by other means. The decay time of the emission from the 4S3/2 state of the Er3+ ion in La0.86Yb0.12Er0.02F3 was measured to be 140±20 μsec if the Er ion is excited directly in the 2H11/2 or 4F7/2 states while the same emission decays with a time constant of 1.1 msec when the phosphor is excited with infrared absorbed by the Yb3+ ions.