Fluorescence Tune Of Upconversion Nanocrystals And Its Application In Ethanol Detection

Rare earth doped upconversion nanoparticles?UCNPS?have attracted more and more attention due to their high signal-to-noise ratio,high sensitivity and high selectivity.It has important applications in military detection,optical-fiber communication,laser anti-counterfeiting,cancer treatment and diagnosis,bio-imaging,solar cells,3D display and other fields,and is expected to become a new generation of nano-probes.Relevant research is mainly focused on bio-imaging and bio-molecular sensing,while the detection of abiological analysis such as organic and inorganic molecules is rarely involved.Based on the principles of surface plasmon resonance and energy resonance transfer,this paper explores the controllable synthesis of UCNPS and its application in the detection of non-biological molecules.1.Upconversion nanocrystals were synthesized by thermal decomposition method and solvent-thermal method respectively.The results showed that the size and morphology of NaGdF₄:18%Yb³⁺/2%Er³⁺upconversion nanocrystals synthesized by solvent-thermal method were consistent.By covering its surface with an inert shell of NaYF₄,the intensity of upconversion luminescence is increased by 8-10 times.The main reason is that the surface defect of the nanocrystalline is repaired by the shell layer,so the upconversion efficiency is improved.2.The surface crystal enhances upconversion fluorescent.Core-shell nanoparticles were treated with ultrasonic oscillations to provide energy for crystals crossing barrier and improve the surface crystallinity.The results show that the core-shell structure can enhance the luminescence,but by removing the surface defects of the inert shell,the enhanced surface crystallization can further enhance the up-conversion luminescence.3.Surface plasmon resonance is used to stabilize the upconversion process,thus realizing the accurate detection of ethanol concentration in the range of 25%⁹0%.Au nanorods with absorption peaks of 525 nm and 928 nm were selected to tune the fluorescent intensity of UCNPs,and the green light intensity at 540nm was linearly correlated with the content of ethanol.The reliability of data detected by Au/NaGdF₄:Yb³⁺,Er³⁺nanoprobe was verified by simulation and repeatability test,so it can be used to identify adulterated liquor.