Au/NaGdF4: Yb3+, Er3+ hybrid fluorescent system for rapid detection of ethanol

Here, we demonstrate the well linear dependence of the fluorescent intensity of upconversion nanoparticles (UCNPs) on the concentration of ethanol at the concentration range of 25%-90% (typical ethanol concentration in Chinese liquors) by employing surface plasmon resonance (SPR) to stabilize the upconversion processes. UCNPs are successfully synthesized by a solvothermal method which emit green light centered at 540 nm under the excitation of 980 nm infrared light. We select Au nanorods with the absorption peaks centered at 525 nm and 928 nm (a wide band covered the wavelength region of 980 nm) for tuning the upconversion luminescence process of UCNPs so that the fluorescence intensity is linearly dependent on the content of ethanol from 25% to 90%. The Au/NaGdF4:Yb3+, Er3+ hybrid fluorescent system may be an ideal strategy for rapidly detecting the content of ethanol in liquor and discerning the adulterated liquor.