ABSTRACT
The surface plasmon resonances of silver nanoshell particles are studied by Green's function. The nanoshell system of plasmon resonances results from the coupling of the inner and outer shell surface plasmon. The shift of the nanoshell plasmon resonances wavelength is plotted against with different dielectric environments, several different dielectric cores, the ratio of the inner and outer radius, and also its assemblies. The results show that a red- and blue-shifted localized surface plasmon can be tuned over an extended wavelength range by varying dielectric environments, the dielectric constants and the radius of nanoshell core respectively. In addition, the separation distances, the distribution of electrical field intensity, the incident directions and its polarizations are also investigated. The study is useful to broaden the application scopes of Raman spectroscopy and nano-optics.
ABSTRACT
In the present article, the high signal-to-noise ratio surface enhanced Raman spectrum of rat serum was analyzed. To be high efficient substrate of SERS, the novel silver colloid was synthesized by microwave method. The characteristic peaks of the rat Raman spectrum were assigned. The mechanism of "hot spot" which was formed by aggregated silver particles was explained by electromagnetic fields enhancements theory, i. e. the excitation of plasmons in the metallic nanoparticles created greatly enhanced local electromagnetic fields, contributing to the major component of the SERS effect. The field distribution at novel silver aggregates exhibits a dramatic enhancement. These strongly localized fields provide an important mechanism for surface enhanced Raman scattering. The surface enhanced Raman spectrum of low quality of component in rat serum was acquired so that the change of body could be known in time. A new method for acquiring abundant information of macro-biomolecule by spectrum means was brought out. It is hopeful to be a novel technique to diagnose diseases in the early stage with serum.
