Optical Properties Of Gold And Silver Nanostructured Materials

The metal nanoparticles exhibit surface plasmon resonance(SPR)effect when interacting with light.The SPR effect greatly enhances the local electromagnetic field on the surface of noble metal nanoparticles.The enhanced local electric field cause enhanced light scattering and light absorption of noble metal nanoparticles,resulting in a strong absorption peak.Therefore,the metal nanoparticles have different optical and nonlinear optical effects than the corresponding bulk materials.These unique characteristics of light,electricity,thermal properties and catalytic activity have good application prospects in the field of nano-optoelectronic devices and biosensors.Compared with other metal nanomaterials,the SPR of gold and silver nanomaterials is in the visible range,so there are many researches on gold and silver nanomaterials.The main contents are as follows:The electromagnetic field simulation technology based on maxwell's equations is introduced.The basic principles of FDTD,numerical stability,absorbing boundary,common excitation source and grid partitioning technology are introduced.The optical properties of gold and silver nanoparticles are studied.Specifically,the effects of size,structure and the refractive index of surrounding medium on optical properties of gold and silver nanoparticles were investigated.It was found that,there is a difference in the absorption peak position of gold and silver nanoparticles in small size and large size.It is also found that the coupling between nano-spheres plays an important role in the spectra of nanoparticles.The optical properties of gold and silver nanorods are studied.The influence of size,structure and refractive index of the surrounding medium on the spectra were investigated by using theoretical simulation.It is found that,there two plasma resonance absorption peaks resulting from transverse vibration and longitudinal vibration respectively.Moreover,the longitudinal plasma vibration can be tuned by changing the aspect ratio or the refractive index of the surrounding medium.The optical properties of gold and silver nano-triangular particles are studied.The effect of the length,structure and refractive index of the surrounding medium on the spectra are investigated.It is found,there are three absorption peaks of single nano-triangular particles in spectra of gold and silver nano-triangular particles,and the new absorption peaks are mainly generated by multipole coupling.The increase of the size of gold and silver nanoparticles caused the red shift of the three absorption peaks.Correspondingly,the spectra and TEM of gold nanoparticles with different shape were provided for testing the validity of the theoretical simulation.It was found that the theoretical simulation was basically consistent with the experimental measurement results.