{"DOI":"10.1039/c5nr08477f","PMID":"26986473","abstract":"
Upconversion photoluminescence is a nonlinear effect where multiple lower energy excitation photons produce higher energy emission photons.
","author":[{"family":"Nadort"},{"family":"Zhao"},{"family":"Goldys"}],"id":"unknown","issue":"27","issued":{"date-parts":[[2016]]},"language":"en","page-first":"13099","publisher":"Royal Society of Chemistry (RSC)","title":"Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties","type":"article-journal"}