The Fabrication Of Gold Nanoarrow Film And The Applications For Surface Enhanced Raman Scattering

The free electrons in the noble metal nanostructure will form a collective oscillation under the action of the external light field,thereby exciting the local surface plasmon resonance.At this time,the incident field energy can be effectively concentrated around the structure,which can form a large local field Enhancement,so it can enhance the interaction between light and matter on the nanometer scale,so precious metal nanostructures show a wide range of application prospects in surface-enhanced Raman scattering,biosensors,biomolecule detection and medical detection.When the noble metal nanoparticles are close to each other,a strong plasmon coupling will occur,which can further increase the local field strength,so it can effectively improve the performance of related devices.Without considering the effects of non-local effects,the smaller the spacing between the nanoparticles is,the more beneficial it is to enhance the effect of light and matter.Therefore,it is necessary to develop effective means to reduce the spacing between the nanoparticles.Although top-down methods such as electron beam exposure are used to control the morphology of the prepared sample,the spacing between the nanoparticles is difficult to shrink to a few nanometers,and the cost is high and the processing is time-consuming.The interface self-assembly method of precious metal nanoparticles based on wet chemical synthesis can prepare a single-layer close-packed precious metal nanoparticle thin film in a large area,where the particle spacing depends only on the thickness of the coating molecular layer,which can greatly enhance the surface Plasmon coupling,in areas such as surface-enhanced Raman scattering,has shown broad application prospects.By adopting the interface self-assembly method,it is now possible to stably and efficiently prepare noble metal nanospheres,nanocubes and other monolayer membrane systems with structural isotropy.In addition,the use of nanoparticles with structural anisotropy(such as nanorods)can adjust the plasmon resonance in a wider frequency range,which can further expand the application of nanoparticle single-layer membrane systems.Compared with nanorods,the nano-arrow structure has a sharper tip,which is very conducive to the enhancement of the local field at these positions.Therefore,the single-layer film system composed of precious metal nano-arrows is expected to produce stronger plasmon coupling,thereby achieving greater local field strength,and further improve the performance of applications such as surface-enhanced Raman scattering.Based on this,two types of anisotropic nanoparticles with high quality gold nanorods and gold nanoarrows were prepared by the seed growth method;using the oil-water interface self-assembly method,we put the gold nanorods and gold in the colloidal solution The nano arrow particles self-assemble into a single-layer film structure,in which the spacing between the nano particles is as low as about 3 nm,which can effectively increase the plasmon coupling;the experimental results show that compared with the nano-gold rod single-layer film The gold nano-arrow single-layer film system can generate a stronger Raman scattering signal.The main content of the paper is as follows:(1)Gold nanorods and gold nano arrowhead structures were prepared by the seed growth method.By changing the amount of gold nanoparticle seeds,the concentration of chloroauric acid,ascorbic acid and other drugs in the growth solution,the parameters such as the aspect ratio of nanoparticles can be effectively adjusted The local resonance peak position can cover a wider band;through the control of growth conditions,the uniformity of the nanoparticle structure in the colloidal solution can be effectively improved,which lays the foundation for the preparation of a single-layer film.(2)In the experiment,the oil-water interface self-assembly method was used to successfully prepare the gold nanorods and gold nanoarrow single-layer film system.The electron microscope test results show that the particles of these single-layer film structures are relatively neatly arranged in a large area.The thickness is relatively uniform.By adjusting the oil-water interface self-assembly method,the structure can be transferred to different substrates while preparing the single-layer membrane structure.(3)In the experiment,the Raman signal enhancement effect of the prepared gold nanorods and gold nanoarrow monolayer film system as the substrate was compared.Raman signal output,these results indicate that the gold nano-arrow single-layer film structure is a good Raman enhanced substrate.