Research On Sensing Properties Of Extinction Type LSPR Based On Noble Metal Composite Nanoparticles

Optical sensing technology based on Local Surface Plasmon Resonance(LSPR)characteristics of metal and its composite nanoparticles has great potential in biomedical fields such as biosensor and accelerated photocatalysis.In this paper,the physical nature of composite structure nanoparticles have been discussed and investigated,which provide new sensing models and theoretical basises for the design of new LSPR nanocomposite structures and the methods of"noble metal nano extinction sensing detection".The main research work includes:Firstly,after discussing the basic theory of Surface Plasmon Resonance and the classical theoretical model of nanoparticles,the Local Surface Plasmon Resonance generation and extinction characteristics of nanoparticles in this paper are simulated by Discrete Dipole Approximation method(DDA)combined with simulation software DDSCAT.Secondly,the factors affecting the extinction characteristics of two-layer metal/compound core-shell nanoparticles based on gold and silver are studied.The extinction efficiency values and visual electric field intensity diagrams are respectively used to reflect the extinction characteristics at directional wavelengths and electric field distributions at fixed wavelengths.After comparing the extinction spectras of different core-shell ratios of nanoparticles based on hybrid theory,the electron reduction abilities of Si₃N₄/Ag,TiO₂/Ag,ITO/Ag nanoparticles and the extinction intensities of ITO/Au,TiO₂/Au,Si₃N₄/Au nanoparticles are ranked from high to low.Then,the gold-based composite ITO/Au core-shell dimer nanoparticle and the corresponding bisymmetric probe extinction sensing system are designed.The extinction spectras of visible-infrared band under different core-shell ratios,dimer spacings and dielectric refractive indexes are simulated.The refractive index sensitivity of the particle is obtained according to the response relationship between the environmental refractive index and the coupled dipole resonance and the octupole resonance.It is found that the particle has high sensitive refractive index detection performance and shows good refractive index linear detection relationship.Lastly,the complete and broken spherical core-shell structures under three-layer of Au,ITO and Ag materials are proposed,and the bow tie-like particle structure of Au/ITO/Ag bisymmetric broken dimer which is sensitive and dependent on incident light is designed.The LSPR formant and LSPR resonance field intensity of this structure are simulated,and the liquid concentration sensing model of bow tie-like particle is established based on the relationship between ethylene glycol liquid concentration and refractive index.It is found that Au/ITO/Ag bisymmetric broken dimer bow tie-like particle has unique and in-depth research value and significance in LSPR local field enhancement and LSPR concentration sensing detection.