Upconversion and anti-stokes processes with f and d ions in solids

The anti-Stokes emissions or upconversion processes, for which emissions was found to exceed excitation energies by 10-100 kT, were presented. The dissolution of nanoparticles (6-8 nm) of Yb-Er- and Yb-Tm doped LuPO 4 as colloids in chloroform solutions was demonstrated. The Nd 3+-Yb3+ codoped YA nanocrystalline cemramics were also studied. It was observed that in thermoluminescence, where traps were emptied by excitation energies of the order of kT, constituted a field of anti-Stokes emission of its own.