Erbium, Ytterbium-codoped ZrO 2 nanoparticles(ZrO 2∶Er 3+ ,Yb 3+ ) were prepared by the sol-emulsion-gel technique. The purpose of the present study is the application of upconversion phosphor in the biological label. In order to make out the mechanism of upconversion under 980 nm excitation the 488 nm pump was used. The influence of temperature on the crystallite phase was studied. The results confirm the upconverted mechanism in ZrO 2∶Er 3+ ,Yb 3+ nanocrystals is due to an energy transfer upconversion(ETU).
We prepared Au/Ag core-shell nanoparticles by growing Ag shell onto 12 nm Au core, using silver nitrate and sodium citrate as the reactants. By changing the molar ratio of Ag to Au, the shell thickness and thus the size of bimetallic particles could be controlled in convenient way. The formation of core-shell structure was proved by UV-Vis spectra, transmission electron microscopy(TEM), etc.. The core-shell particles showed a more narrow size distribution than Ag colloid prepared without Au core. The SERS activity of the core-shell particles was investigated by using 2,4-dimethylpyridine as the probe, which strongly indicated their potential application in SERS substrate materials.
The characteristics of the LB films of Schiff base aluminium(Ⅲ), tris(2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium(Ⅲ)[Al(TA12)_3], were studied. The surface pressure-area(π-A) isotherm of Al(TA12)_3 in the pure water subphase was investigated. The molecular area, 0.48 nm^2, is one-third of the expected value that indicates the formation of an aggregate. The Langmuir-Blodgett(LB) films of Al(TA12)_3 were transferred and characterized. The UV-Vis spectra and the AFM image both confirmed that the J-aggregates formed. The polarized UV-Vis spectra indicated that the complex plane had to be oriented with an angle of about 30° to the substrate surface. The IR spectra suggested that the complexation took place between aluminium ions and the oxygen atoms of the ligand rather than the nitrogen atom.
LIAN WeiCAO WeiWANG GangWEI LiHONG XiaSHEN Dong-fangLIU Chun-yanSHAO Hui-boBAI Yu-bai
Gold nanoparticles, prepared by the Frens method, have been electrostatically assemblied onto mica substrates treated with different concentration of MnCl\-2 solution. The assemblies have been investigated by means of atomic force microscopy(AFM). The immersing time of bare mica in Mn\+\{2+\} solution and the concentration of Mn\+\{2+\} solution both have significant effect on the assembled process of gold nanoparticulate monolayer. The coverage of gold particles shows periodical evolution on the immersing time of mica in MnCl\-2 solution. The higher is the concentration of MnCl\-2, the shorter is the time to attain maximum coverage. An ion\|exchanged and layer\|dissociated mechanism is put forth to explain the experimental results above.
We use 8 nm magnetite nanoparticles as "ink", self assembly monolayer(SAM) of bovine serum albumin(BSA) as "paper" to generate arbitrary structures at micro or nanometer scales in the DPN procedure. AFM and LFM are used to image the patterns. The height profile of pattern is about 8 nm, which is consistent with the diameter of magnetite nanoparticles. It means that the magnetic monolayer pattern has been obtained. The SAM of BSA is measured by diffuse reflection IR spectra and the data is coincided with the one of the literature. After writing the magnetite "ink", the band of magnetite appears at 570 cm -1 , which gives a further proof.
