The Study On The Preparation Of Gold Nanoparticles, Modified-gold Nanoparticles And Their Optical Properties

The preparation of gold nanoparticles has been known for a long time, until last century, gold nanoparticles whose size below l00nm could have been preparated arbitrarily. Therefore from this century, the study of gold nanoparticles have been transfered to two aspects: first is understand the action of gold nanoparticles limiting electrons; second is find new characteristic for gold nanoparticles. Understand the action of gold nanoparticles limiting electrons is that understanding gold nanoparticles surface plasmon oscillation on different conditions.This paper has done on preparation of gold nanoparticles and modified gold nanoparticles, and studying the changing of modified gold nanoparticles surface plasmon oscillation.1. The preparation of gold nanoparticles and the study of their surface plasmon resonanceWe had preparated gold nanoparticles of different size through two-step approach, one-step approach and seeding growth approach. UV-Vis image and TEM image indicated that surface plasmon resonance absorbance had a red shift with the argument of the sizeof the gold nanoparticles.2. The preparation of Ag-coated Au nanoparticles and the study of their optical propertiesSeveral kinds of different Ag-coated Au nanoparticles had been preparated, TEM indicated that Ag-coated Au nanoparticles had different size with the different AgNO3. UV-Vis image indicated that surface plasmon resonance absorbance had a blue shift with the increase of silver shell. SERS showed that when the silver shell reached acertain degree, the Ag-coated Au nanoparticles had a same SERS with silvernanoparticles.3. The preparation of DDP-modified gold nanoparticles and mechanism forred-shift in the surface plasmon resonance absorptionGold nanoparticles were reduced by tri-sodium citrate and then modified by DDP (O,O ' -Dioctadecane dithiophosphate) . IR image indicated that DDP had a covalent chemical interaction with the surface of the gold nanoparticle. TEM showed that DDP-modified nanoparticles had a similar size with the original nanoparticles. At the same time it had been found that the surface plasmon resonance (SPR) absorbance of the DDP-modified gold nanoparticles had a large red shift. Furthermore, the jellium model was used to analyze the characteristic of SPR; the dipole model and the IR spectrum were used to form a new dipole model.,It can be used to explain the mechanism of the red shift.4. The preparation of DDT-modified gold nanoparticles and the dicuss of theiroptical propertiesWe preparated DDT-modified gold nanoparticles using Brust approach. TEM showed that DDT-modified gold nanoparticles had a uniform size and could be self-assemblyed to form a two-dimensional superlattice on a certain concentration; We tried to assembly this nanoparticles to slippery substrate and studied their optical preproperties.