Homogeneous Coating And Gold Nanosystems For NaYF 4 :Yb 3+ /Er 3+The Fluorescence Regulation Effect Of Nanoparticles

Being of peculiar nature in nano-materials brought new change to human. The new technologies such as biological probe, nano-machines, etc. That make the rare earth doped nanometer materials become one of the most high-profile luminescent material. Enhanced the fluorescence detection sensitivity of rare earth doping nanoparticles, that's the key in the development of its applications in micro devices and biological medicine, etc. This article with thermal decomposition prepared the NaYF₄: Yb³⁺/Er³⁺ nanoparticles. It was found that the fluorescence enhanced by adjusting the reaction conditions which control the size of the sample and the fluorescence intensity, also through homogeneous coating and introduce gold nano-system to adjust the fluorescent properties of the samples. Specific work is as follows:1) By control the reaction conditions of thermal decomposition:time and stirring rate. Found that under the same reaction conditions, extend the reaction time, nano-particles size become bigger, the greater the degree of crystalline phase, the stronger the fluorescence intensity. When the reaction stirring speed become slower, the bigger the nano-particles size, the degree of crystalline phase become more greater, the stronger the fluorescence intensity.2) Studies the core-shell structure on the influence of the fluorescence intensity about nanoparticles, through coat the different thickness of shell. Found that fluorescence intensity have enhanced, fluorescence lifetime have extended. And with the increase of the thickness of the shell fluorescence intensity increased, fluorescence lifetime extended. Fluorescence enhancement can be roughly divided into the following two reasons:a. The cladding layer outside the nuclear repair the defect on the surface of the nanoparticles. b. The cladding layer play a isolated role, isolated the impurities in nanoparticles surface and the defects in adjacent nanoparticles surface decrease the fluorescence intensity.3) Based on precious metals surface plasmons resonance principle, research the Au nano-structure impact on fluorescent intensity of NaYF₄:Yb³⁺/Er³⁺ and NaYF₄:Yb³⁺/Er³⁺@NaYF₄ nanoparticles. By introduce the golden nano-rod in the rare earth nanoparticles solution, observe the changes of fluorescence intensity. Found that along with the increase in gold concentration, fluorescence intensity is increased after decreased. b. Through periodic spin in the nano-structure of nanoparticles of different shell thickness control luminous center distance with periodic gold nanostructures, study the changes of fluorescence intensity. Found that with the increase of nanoparticles coated layer thickness, fluorescence intensity increased multiples, first after rising downward trend. It's the main cause of the fluorescence change of the rare earth nanoparticles and distance on the surface of the gold nanoparticle system change. Can occur when the distance between them in the local surface from the scope of primary resonance, such as metal surface between the nanoparticles and magnetic field strength increase, amount of glow ion when quantum rate increased, the fluorescence intensity increases. The reason of fluorescence enhancement is the system of gold nanoparticles surface plasmons resonance effect.