Investigations on multi-photon emissions of Nd3+-sensitized core/shell nanoparticles

Ultraviolet (UV) upconversion emissions originated from multi-photon process of Tm3+ were studied with Nd3+-sensitized nanoparticles. Coexistence of Nd3+ and Yb3+ is essential to mediate the energy transfer via the core/shell interface. Although the upconverting process is initiated with Nd3+→Yb3+, the short-wavelength emissions are intrinsically coming from four- and five-photon process