Construction Of Nanogap Coupling Structure And Its Plasma Resonance Properties

Nanostructured materials exhibit completely different properties behavior from macroscopic materials due to their high surface area and changes in the atomic distribution inside and on the surface of their materials.Among them,noble metal nanostructured materials have peculiar Surface Plasmon Resonance(SPR)properties.When they interact with incident electromagnetic waves,they can lead to an increase in local electromagnetic field strength.SPR is sensitive and highly controllable to the size,material,morphology and dielectric environment of nanostructure.Based on this special SPR property,noble metal nanostructured materials have shown great application value in sensing,optics,and electronics.Especially,when nanoscale gaps are introduced into precious metal nanostructured materials,the metal nanostructures coupled on both sides of the gap can cause a violent plasmon resonance effect,and the electromagnetic field strength in the gap is significantly increased.When the gap reaches the order of sub-10 nm,the super-strong electric field generated in it can be used for the determination of single molecules.In order to meet the needs of nanoscience research and commercial development of nanogap devices,how to produce the required nanogap structures in large quantities with simpler,more efficient and cheaper processes has always been the goal of people's efforts.In this paper,a variety of nanogap coupled structures were prepared based on nano-skiving technology,and the corresponding plasma properties and potential related applications were studied.In chapter 2,we combined nano-skiving technology with physical vapor deposition to achieve the preparation of homogeneous and heterogeneous nanogap coupled structures by changing the deposition of different noble metal materials.Because the metallic silver has better optical properties than gold in the visible light range,and the existence of phase hybridization mode between gold and silver leads to the enhancement of local surface plasmon resonance of heterogeneous nanogap,the prepared gold and silver hetero-nanogap coupling structure has stronger electromagnetic field enhancement than homogeneous nanogap coupling structure(gold-gold coupling gap,silver-silver coupling gap).At the same time,this preparation method is easy to operate,does not need complex and expensive instruments and equipment,as well as strict experimental conditions,suitable for mass production.Gold and silver heterostructures have potential applications in SERS substrates,plasma devices and catalytic reactions.In Chapter 3,we continued to use nano-skiving technology to first prepare the gold-polymer-gold nanogap coupling structure.Then the quaternized polymer nanogap made the surface of poly tetra vinylpyridine(P4VP)positively charged and immersed it in a gold sol coated with negatively charged citric acid.Under the action of polymerassisted electrostatic assembly,self-assembling gold nanoparticles at the polymer nanogap were realized.Self-assembled nanoparticles of different sizes can be achieved by adjusting the size of gold nanospheres.Gold nanogap coupling nanoparticle structure has multiple nanogap at the same time(gap between linear nanoparticles,gap between nanoparticle and gold nanowire,and gold nanowire-polymer-gold nanowire gaps),compared to gold-polymer-gold nanogap has stronger electromagnetic field strength.In addition,the electromagnetic field distribution of gold nanogap coupling nanoparticles structure under different polarized light was theoretically studied.The preparation method has the advantages of simple operation,short cycle and low cost,and the prepared structure has potential application value in many fields such as surface enhanced Raman scattering substrate,DNA sensing,and nano-antenna.