Abstract
Infrared to visible and ultraviolet upconversion in Nd
3+ doped KPb
2Cl
5 crystal is reported. Three intense bands have been observed at 535, 595, and 668 nm coming mainly from levels
4G
7/2–
4G
9/2, together with emissions at 362, 388, 420 and 456 nm coming from level
4D
3/2, and a peak at 435 nm, corresponding to the
2P
1/2
→
4I
9/2 transition. A study of the upconversion mechanisms has been carried out that includes the upconversion emission dependence on the wavelength and intensity of the pumping light together with a comparison of the luminescence decays after infrared excitation and after direct one photon excitation of the emitting levels. The results indicate that two- and three-body energy transfer upconversion processes are responsible for emissions from levels
4G
7/2–
4G
9/2 and
4D
3/2 respectively, while level
2P
1/2 is populated by either energy transfer upconversion or excited state absorption depending on the pumping wavelength.