upconversion luminescence of rare earth doped nanocrystalline
In recent years, nano-science and technology with the development of fluorescent nanoparticles of rare earth doped optical properties of its unique optical, electronics, informatics and biology to show potential applications. 50 years since the last century, this phenomenon has been found on the conversion since the conversion luminescence materials has been a hot research field of materials science is one. Upconversion of rare earth doped nano-materials in the biological markers, fluorescent in vivo imaging, laser and optical fiber communications has wide application areas. Upconversion luminescence materials and other fluorescent materials, compared with the narrow emission line, light stable, no light bleaching, fluorescence signal to noise ratio advantages, so in the biomedical field have important potential applications. Recently, researchers have already successfully used in upconversion materials, cell imaging, immunoassay and DNA detection. In order to achieve its wide range of biomedical applications, people want more efficient preparation of the starting light, smaller size, better dispersion of upconversion luminescence materials. The main focus of this paper upconversion of rare earth doped nanocrystals and biological application of a series of work, and got some innovative results, the following key elements:
We supply Magnetic Product,Neodymium magnets,Rare earth magnets,Permanent magnets,in Magnetic Product,Neodymium magnets,Rare earth magnets,Permanent magnets we are your best china magnets suppliers choice.Please contact us!
Xiamen Everbeen Magnet Electron Co.,Ltd. http://www.999magnets.com
Add:Unit H, 4F Rihua Mansion, No. 8 Xinfeng 2nd road, Torch Hi-Tech Zone, Xiamen, China.
Tel:0086-592-5781916
Fax:0086-592-5123653
E-mail:info@china-magnet.net
1. Using combination of sodium citrate as a chelating agent during the hydrothermal synthesis of different size and morphology of cubic and hexagonal structure NaYF_4: Yb ~ (3 +), Er ~ (3 +) nanocrystals. The amount of F ˉ ion, the amount of citric acid, hydrothermal temperature and hydrothermal time parameters on the morphology of nanocrystals, size, structure and upconversion luminescence properties were analyzed, and NaYF_4: Yb ~ (3 +), Er ~ (3 +) upconversion nanocrystals luminescence properties were studied. Study found that excessive F ˉ ion can reduce the crystallization temperature of hot water at a relatively low temperature, you can get a better crystalline nanocrystals; by adjusting the amount of sodium citrate can effectively control the size of the sample , morphology and crystal structure of rare earth cation of citric acid molecules and the strong chelating ability to effectively control NaYF_4: Yb ~ (3 +), Er ~ (3 +) nanocrystals growth rate, phase transition time, its NaYF_4 nuclei hexagonal {0001} planes of the selective adsorption, the crystal growth process, in the direction of the six symmetry: ± [101_0], ± [011_0] and ± [11_00] growth rate is relatively quickly, forming a hexagonal NaYF_4 sub-micron film. In the 980 nm laser excitation, the observed cubic phase nanoparticles and hexagonal sub-micron chip upconversion luminescence, the green and red upconversion luminescence process belong to the two-photon process. Relative to the green emission, the sample is relatively strong red upconversion emission. Experimental results show that the sample molecules on the surface energy of organic acid groups caused by vibration of multi-phonon relaxation process and Er ~ (3 +) ion cross relaxation interaction between the samples of the red upconversion emission is the main strong reasons.
2. With polyethylene imine (PEI) as a surfactant by hydrothermal synthesis, the first time, the porous structure of the synthesized hexagonal NaYF_4: Yb ~ (3 +), Er ~ (3 +) hollow nanospheres. Nitrogen adsorption / desorption curves of the porous nature of the samples proved. Through the PEI concentration, hydrothermal temperature and hydrothermal time parameters on the morphology, size and structure effects discussed hexagonal NaYF_4: Yb ~ (3 +), Er ~ (3 +) hollow nano- The growth mechanism of the ball and upconversion luminescence properties. Experimental results show that the appropriate concentration of PEI and hydrothermal reaction conditions are hexagonal NaYF_4: Yb ~ (3 +), Er ~ (3 +) key to the formation of hollow nanospheres factors. Hydrothermal time on the preparation of different samples were characterized by analysis, the sample experienced from the cubic phase NaYF_4: Yb ~ (3 +), Er ~ (3 +) nanocrystals to the hexagonal NaYF_4: Yb ~ (3 +), Er ~ (3 +) self-assembled nanowires, to the hexagonal NaYF_4: Yb ~ (3 +), Er ~ (3 +) hollow nanospheres and morphology evolution of the phase transition process, PEI induced Ostwald ripening process is the formation of the sample the main mechanism. Excitation at 980 nm, the particles showed strong upconversion luminescence. As a high doping concentration, adjacent Er ~ (3 +) ions between the strong cross relaxation, combined with the organic high-energy vibration of the sample surface caused by multiple groups phonon relaxation process of the sample showed relatively strong red upconversion emission characteristics.
3. PEI with different molecular weight polymer surfactant, water / alcohol solution as the solvent, the use of water, heat / hot solvent the size controlled synthesis of water-soluble NaYF_4: Yb ~ (3 +), Er ~ (3 +) nanoparticles. It was found that the same hydrothermal conditions, with high molecular weight polymer (HPEI) samples synthesized polymers than low molecular weight (LPEI) synthesis of smaller sample size. It is noteworthy that, in the same 980 nm laser excitation power, the small size of the sample upconversion under the same conditions than the large size of the upconversion luminescence intensity of samples. Combination of crystal growth theory, we believe that the difference between crystalline conversion emission intensity on the sample for different reasons, high molecular weight polymer can reduce the growth rate of particles, in favor of small size, the crystallization and good particle generation. Cytotoxicity assays and fluorescence immunoassay experiments show that the prepared samples have good biocompatibility.
