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, Supporting Information Available ? synthesis and characterization of the nanoparticles

, ? upconversion of the nanocrystals compared to a single crystal

, ? upconversion quantum yield measurements and results

, ? excitation in the excited state for the 1 G 4 ? 3 H 6 emission

, ? emission spectra of the 1 D 2 ? 3 H 6

, ? measured spectra of the sun-like lamp used