Comparative Study on SERS and Stability of Negative Silver Colloids
LI Qing-yu1,LI Shi-rong2,SI Min-zhen2*,ZHANG Peng-xiang3
1. Department of Basic Courses, Southwest Forestry College, Kunming 650224, China 2. Department of Physics and Electronic Science, Chuxiong Teacher’s College, Chuxiong 675000, China 3. IAMPE Kunming University of Science and Technology, Kunming 651000, China
Abstract：Negatively charged colloidal nano-silver particles were prepared by the colloidal chemical method. A 1.7% solution of silver nitrate(2 mL) was diluted with deionized water to 100 mL. A 1% solution of tannic acid(1 mL) was added dropwise to the solution stirring, then a 1% solution of potassium carbonate anhydrous(3-4 drops) was added to the mixed solution. Finally, a red-brown silver sol was obtained. It was testified that the silver sol is a negatively charged colloid by experiment of electrophoresis. The negative silver colloids (for short, old NCS) were kept on at the room temperature two year ago in order to test its SERS and stability. The sizes of particles were determined by Hitachi H-800 transmission electron microscope. Absorption spectroscopy and SERS were used to determine the main properties. Absorption spectra were obtained with UV-2401PC. Raman spectra were recorded with RENISHAW MIK 2000 Raman micro-spectroscopy. The 514.5 nm line of an argon ion laser with about 3 mw was used. Compared with the newly perpared negative silver colloids (for short, new NCS). It was found that the mean diameter of the old NCS was larger than the new NCS; old NCS had absorption maximum at 431 nm but new NCS at 418 nm, the absorbance spectrum of old NCS had a 12 nm red shift, and the red shift rate is about 0.5 nm/month; Both strong SERS spectra were observed when cationic molecules of fuchsine basic and neutral molecules of alcidine orange adsorbed on old NCS and new NCS; For cationic molecules of methylene blue, the SERS is stronger on new NCS than old NCS; but no SERS was observed for the anionic molecule of benzoic acid both on new NCS and on old NCS.
李清玉1,李世荣2,司民真2*,张鹏翔3 . 负电性纳米银溶胶SERS活性及稳定性的比较研究[J]. 光谱学与光谱分析, 2007, 27(02): 299-301.
LI Qing-yu1,LI Shi-rong2,SI Min-zhen2*,ZHANG Peng-xiang3 . Comparative Study on SERS and Stability of Negative Silver Colloids. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2007, 27(02): 299-301.
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