Spectral Properties Of The Se And Au Nanoparticle Systems

Part 1Selenium nanoparticle were prepared by heating, which used hydrazine hydrate as reducing agent and used polyvinyl alcohol as stabilizer. The results showed that the selenium colloids have better-dispersion and stability .The average diameter is 12 nm. The procedure has rapidity and convenience .The absorption spectrum and Rayleigh scattering spectrum of Selenium colloid were studied. The maximum absorption peak of selenium colloid is at 580 nm. There are two Rayleigh scattering peaks at 470nm and 570 nm. Owing to quanta colored effect, the Rayleigh scattering peak at 570nm is characteristic Rayleigh scattering peak,namely resonance scattering peak(or resonance Rayleigh scattering peak) . The peak at 470 nm is mainly due to that absorption of light resource at 470 nm is strongest The influence of the dyes on the Rayleigh scattering of Selenium nanoparticle has also been studied, such as bromophenol blue(BB), methyl orange(MO), bromcresol purple(BP) ect. It is found out that the absorption of dye molecules is one of important factors to result to Rayleigh scattering peak and valley.Part 2Composite gold nanoparticles were prepared by heating system of HAuCl4- fluorescence dye -Tri-sodium citrate (TSC). In this paper, the absorption spectra, fluorescence spectra and synchronous scanning spectra of the system were studied before and after fluorescence quenching. It has been found out that absorption spectra and Rayleigh scattering spectra of composite gold nanoparticles are similar to gold nanoparticle. There is a Rayleigh scattering peak at 580nm both the composite gold nanoparticles and gold nanoparticle. The reason is that composite gold nanoparticlesand gold nanoparticle have same solid (gold)-liquid interface .The HPLC of the system has no peak like gold nanoparticle, if fluorescein was added before reacting. The HPLC of system has a peak like fluorescein, if fluorescein was added after reacting. Therefore, the core/shell structure of composite gold nanoparticles was proved once more. Fluorescent molecules are wrap up inside Composite gold nanoparticles and no more interact on excited light, So that there is fluorescence quenching.Part3The spectral properties of (Au)n-KCl, (Au)n-(FR)k-KCl and (Au)n-(RDG6G)k-KCl were studied by using absorption spectra, fluorescence spectra and Rayleigh scattering spectra. For the system of (Au)n-KCl, the negative charges on (Au)n surface are neutralized by K+, so (Au)n aggregate into bigger Au nanoparticle. The intensity of Rayleigh scattering of system enhances greatly. For the system of (Au)n-(FD)k-KCl, fluorescence dye molecules are firstly absorbed on the surface of Au nanoparticle. When KCl are added, the negative charges of (Au)n surface which are not occupied by dye molecules are neutralized by K+, the smaller Au nanoparticles turn into bigger nanoparticles. The intensity of Rayleigh scattering of system enhances. Fluorescence dye molecules are wrap up among gold nanoparticles, and no more interact with the excited light, So that there is fluorescence quenching.