Direct Evidence of a Surface Quenching Effect on Size‐Dependent Luminescence of Upconversion Nanoparticles

A series of Yb/Tm co-doped NaGdF4 nanoparticles without or with a thin surface protection layer provide direct evidence of a surface quenching effect on size-dependent upconversion luminescence (see picture). The coating preserves the optical integrity of the nanoparticles (right-hand spectrum) and minimizes emission loss induced by surface quenching. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other…