Frenkel Defect Responsive Upconversion Through High-Energy Radiation

摘要

Near-infrared light excitable upconversion nanocrystals are extensivelyapplied in anticounterfeiting, optical imaging, and biomedicine, whereinmany mechanistic endeavors are made to manipulate energy transfer throughchemical engineering. However, how external stimuli such as high-energyradiation (X-ray) influence the energy transfer of these upconversion nanoparticlesremains poorly understood. Here a new strategy for energy transfermodulation through X-ray irradiation in Yb~(3+) and Tm~(3+) co-doped nanoparticlesis reported. Mechanistic studies indicate that X-ray induced Frenkeldefects in crystal lattices, other than the variation of lanthanide valence orcrystal symmetry, lead to energy mismatch between adjacent Yb~(3+) sensitizersand the resultant inefficient energy transfer from sensitizers to activators.Based on these findings, high-contrast X-ray imaging and long-term informationstorage (over 50 days) using nanoparticle-containing flexible films aredemonstrated. This work offers insights into the understanding oflight-matter interaction by high-energy radiation and provides a promisingmethodology for long-term information storage and X-ray imaging.