Quantum cutting in nanoparticles producing two green photons

A synthetic route to nanoscale NaGdF4:Ln is presented which allows for quantum cutting based on the Gd–Er–Tb system. This shows, that cross-relaxation and other energy transfer processes necessary for multiphoton emission can be achieved in nanoparticles even if the large surface and the potentially huge amount of killer traps would suggest a lack of subsequent emission.