Ultraviolet upconversion emissions of Gd3+

Under 980 nm excitation, upconversion (UC) emissions in the U-V range of 270-320 nm were observed in nanocrystals Y0.795-xGdxYb0.2Tm0.005F3 (x=0, 0.1, 0.2, 0.5, and 0.795), which were synthesized through a hydrothermal method. These UC emissions can be assigned to the transitions of I-6(J), P-6(J) -> S-8(7/2) (Gd3+), and P-3(0)/I-1(6) -> H-3(6) (Tm3+). The energy transfer from Tm3+ to Gd3+ plays a crucial role in populating the excited states of Gd3+. The shortest wavelength of upconverted emission converted from the infrared region was demonstrated here. (C) 2008 Optical Society of America.