Theory of antistokes sensitized luminescence

The effect is considered of the migration and back transfer on the radiationless summation of electron excitations according to the successive sensitization scheme. Expressions have been found for the effective energy transfer rates at the first and second stages of sensitization, as well as for the quantum yield of antistokes luminescence via the elementary process probabilities. The theory is used for estimating the efficiency of the summation of electron excitations in a crystal of LiYF4 activated by Yb3+ and Ho3+. For this system the probabilities are calculated of elementary processes of energy transfer and also the rate of migration of Yb3+ excitations. The theoretical results are compared with experimental data