10.1007/s10789-008-1001-2

Abstract

Data are presented on the 300-K photoluminescence in GaS crystals doped with Er 3+ or codoped with Er 3+ and Yb 3+ . IR excitation ( λ ex = 976 nm) gives rise to anti-Stokes luminescence in GaS:Er 3+ (0.1 at %) and GaS:Er 3+ ,Yb 3+ (0.1 + 0.1 at %) and leads to an increased intensity of the emission due to the 4 I 11/2 4 I 15/2 transitions. The anti-Stokes luminescence is shown to result from consecutive absorption of two photons by one Er 3+ ion, and the increased intensity of Er 3+ luminescence in GaS: Er 3+ ,Yb 3+ is due to energy transfer from Yb 3+ to Er 3+ .