The present relates in general to upconversion luminescence (“UCL”) materials and methods of making and using same and more particularly, but not meant to be limiting, to Mn2+ doped semiconductor nanoparticles for use as UCL materials. The present invention also relates in general to upconversion...http://www.google.es/patents/US7501092?utm_source=gb-gplus-sharePatente US7501092 - Manganese doped upconversion luminescence nanoparticles
