UP-CONVERSION DYNAMICS OF ER3+ DOPED RBGD2BR7

MR-to-VIS upconversion mechanisms upon excitation into I-4(11/2) aroun d 980 nm in the Er3+ doped low energy phonon host material RbGd2Br7 ar e identified and analyzed. The small energy difference between the fir st excitation step I-4(15/2)-->I-4(11/2) and the second step I-4(11/2) -->F-4(7/2) leads to a competitive situation of excited state absorpti on and energy transfer upconversion processes. Their relative efficien cy strongly depends on the excitation energy and temperature. Fingerpr inting techniques based on the temporal evolution of the upconverted l uminescence after a IO ns laser pulse are used to distinguish the two mechanisms. Rate constants for the relevant processes are determined. With W-t = 68 s(-1) at 10 K the energy transfer step in the upconversi on process is comparable to Er3+ doped CsCdBr3. (C) 1997 American Inst itute of Physics.