ON THE DISTRIBUTION OF ENERGY BETWEEN THE TM F-3(4) AND HO I-5(7) MANIFOLDS IN TM-SENSITIZED HO LUMINESCENCE

A theory on the distribution of energy between the Tm F-3(4) and Ho I- 5(7) manifolds in Tm-sensitized Ho materials is presented. A rate equa tion approach is utilized to arrive at an expression for the temperatu re-dependent equilibrium constant, Theta. Experimental support for thi s calculation is obtained by two different experimental procedures. Ap proximations used in the theory and the limits of applicability are al so discussed. In the course of the development of the theory, a distin ction is made between low and high excitation regimes, and criterion f or applicability are given. Equations for the fractional population of Tm and Ho ions of the total excited state population in the low excit ation density limit are derived in the context of the present theory, which differ from those widely used in the literature.