The Preparation Of Nano Silver Particles By Magnetron Sputtering And Using For Fluorescence Enhancement

The research on luminescence enhancement of fluorescent materials based on the plasmon resonance characteristics of nano-metal particles has become a hot topic in the research and application of nano-metal materials.The silver nanoparticles can generate an obvious absorption band between UV-light and Visible light,attributed its surface plasmon resonance effect,and have a very good application prospect in the fields of fluorescence enhancement,biomedical detection and promotion of photocatalysis.In this paper,we focused on the preparation of nano silver particles and the enhancement of luminescence of fluorescent materials by silver nanoparticles.The main points are as follows:（1）We prepared Ag nanoparticles in the surface of barium titanate thin film by magnetron sputtering,in which sputtering alternately sliver target and barium titanate target and annealing in nitrogen atmosphere.Using SEM,UV spectrophotometer and other means to analyze samples,the prepared silver particles were uniform in shape,and most of the particle diameters were distributed between 20-30 nm,and the plasma resonance absorption characteristics was strong.Moreover,we focused on the influence of annealing temperature and layer number on the morphology and plasma resonance absorption property.The increase of annealing temperature contributed to the fusion and diffusion speed of silver particles,and then improved the density and uniformity of the particles.The plasma resonance absorption characteristics was also enhanced.The optical annealing temperature was determined to be 500℃by comparison.The changes in the number of circulating layers had an important effect on the density of nano silver particles.Although the size of the particles was reduced with the increase of the number of circulating layers,the density of the particles was increasing.The improvement of density made the plasma resonance absorption property improve.When the fixed silver sputtering thickness was 2nm and the barium titanate sputtered thickness was 10nm,the best layer number was three.The silver nanoparticles were also affected by the surrounding environment.The absorption peak of nanosilver particles can be regulated by changing the dielectric environment around the nanoparticles.The absorption peaks of the silver nanoparticles had a significant red shift on the surface of the barium titanate compared to the surface of the quartz wafer.By introducing barium titanate with high dielectric parameter characteristics,the absorption peak of the silver particles was moved to the visible light range,which facilitated the coupling of the absorption peak of the silver particles with the fluorescence.（2）The CdSe quantum dots were combined with the prepared nano-sliver particles by the method of dipping.We chose 450 nm as the excitation wavelength to facilitate the close coupling between the excitation wavelength and the plasmon resonance absorption peak of the nanosilver particles.As a result,it was found that the luminescence intensity of the CdSe quantum dots was enhanced,and the maximum enhancement could reach 8.7 times.The enhancement of luminescence had an important relationship with the plasma absorption characteristics of nanosilver particles.We also discussed the mechanism of the enhancement.The most likely reason was that the interaction between the nano sliver particles and excitation light enhanced the local electric field around the CdSe quantum dots and increased the excitation efficiency,which was attributed to resonance coupling.（3）BaTiO₃ colloids doped with rare earth ions Er³⁺-Yb³⁺were prepared by sol-gel method.The colloids were spin-coated onto the surface of the prepared nano silver particles and excited using a 980 nm laser.Due to the existence of nano silver particles,the luminescence intensity of the rare earth ion Er³⁺-Yb³⁺up conversion was enhanced and the enhancement multiplier could reach 5.7.Through analysis,this luminescence enhancement may be mainly due to the influence of the excitation light on the nanosilver particles,generating a plasmon resonance effect,enhancing the intensity of the local electric field,and further achieving the effect of fluorescence enhancement.The silver particles prepared in this paper had the advantages of high unit density,uniform surface dispersion,regular morphology,and uniform particle size distribution.It can be applied to the field of fluorescence enhancement.