scheme1
From: Energy transfer process, luminescence optimizing and various applications of lanthanide complexes
Scheme 1. Yb2Er-centered energy-level diagrams derived from the observed emissions associated with 3.5 equiv of fluoride and possible mechanisms highlighted. This figure is used with permission from Wiley-VCH GmbH[45]. DL: Downshifting luminescence; UCL: upconversion luminescence.
