Intense red upconversion luminescence in Er3+-sensitized particles through confining the 1532 nm excitation energy
Lanthanide-doped upconversion (UC) materials are commonly excited by 700–1000 nm laser because of Yb 3+ (980 nm excitation) and Nd 3+ (808 nm excitation) are typically used as sensitizers. However, the excitation band located in the second near-infrared window (NIR-II, 1000–1700 nm) demonstrates the deeper penetration in biological tissue with minimum tissue scattering and autofluorescence. Herein, intense red UC emission in Er 3+ -sensitized NaLuF 4 particles under 1532 nm NIR-II excitation is presented. Red UC luminescence is significantly enhanced and purified through confining the 1532 nm excitation energy by Ho 3+ and Tm 3+ mediators, via an energy back transfer pathway (Er 3+ → Ho 3+ → Er 3+ and Er 3+ → Tm 3+ → Er 3+ ). Furthermore, when the particles injected into the fresh beef, red UC luminescence can be distinctly observed from the inside of beef under 1532 nm NIR-II excitation, implying the deep penetration of 1532 nm NIR-II excitation and 660 nm red UC emission. Our results suggest that bright red UC luminescence from Er 3+ -sensitized NaLuF 4 crystals with 1532 nm NIR-II excitation may be suitable for deep optical imaging .
危险品化学品经营许可证（带存储）