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Research On Nano-scale Etched Single Metal Nanowire And Structures Containing"Hotspot" In3-dimensions As Effective Surface-Enhanced Raman Spectroscopy(SERS) Platforms

Posted on:2015-01-17Degree:MasterType:Thesis
Country:ChinaCandidate:Y GeFull Text:PDF
GTID:2251330428481046Subject:Optics
Abstract/Summary:PDF Full Text Request
Since the21st century, researches about nanotechnology had been developed signifcantly. The noble metal nanomaterials, especially silver, exhibiting outstanding optical properties. Under the electric field of incident light with specific wavelength, free electrons of noble metal nanomaterials participate a collective oscillation with incident light, forming the Surface Plasmon Resonance (SPR), which makes nanomaterials’electromagnetic field greatly enhanced. The main enhancement mechanism of Surface Enhanced Raman Spectroscopy (SERS), appling the electromagnetic field enhancement, to enhance the Raman signal of molecule which in the gap of the noble metal nanomaterials. In SERS field, the gap usually called the Raman "hot spots". How to use a simple method to prepare SERS platforms with a large number of Raman "hot spots" has been the main research of SERS now. Based on this, this paper’s main research work carried out as follows:Firstly, Silver nanowires were synthesised using the wet-chemical method. The wires have smooth surfaces, which is about300nm in diameter, length can be up to10μ m. In recent years, studies on surface plasmon propagation property of silver nanowire have achieved breakthrough, so great interests and attention were attracted by this one-dimensional nanomaterial. Besides, on the optical platform which designed by us, we realized the silver nanowires’ transmission with laser wavelength of633nm, and summed up the relationship between lengths of silver nanowire and the light transmission efficiency of silver nanowire.Secondly, the surface morphology of a single smooth silver nanowire was modified by designing a simple chemical reaction, obtaining a new type of single silver nanowire SERS substrate with a large number of "hot spots". By controlling the reaction conditions, different modification degree of silver nanowires has been obtained, the surface morphology of it were observed under Scanning Electron Microscope (SEM). Selecting4-mercaptobenzoic acid (4-MBA) molecules as the Raman probe molecules, we found after the nanometers-level etching, single silver nanowire, get a higher SERS enhancement factors comparing to smooth single silver nanowire. In addition, Raman Image and SERS polarization characterisitics of a single silver nanowire were taken before and after modification, indicating that the design of the surface modification of silver nanowires is a kind of excellent SERS active substrate.Thirdly, we tried to synthesis gold nanowires with length larger than10μ m, and diameter greater than100nm. Using the same etching method, get the new surface morphology of single gold nanowire, is largely different from single silver nanowire. In addition, by controlling the reaction conditions, we prepared micrometer gold prims with different sizes. We also get some micrometer gold prims with six fans.Finally, By laying nylon-66nanofibers, evaporating nano silver film, and spining silver nanoparticles, we built a nano silver film-silver nanoparticles coupling SERS substrate,which containRaman "hot spots" in three-dimensions. The substrate overcomes the shortcomings of the traditional substrate which contains Raman "hot spots" only in two-dimensions, and combines the advantages of nanofibers, like low costs, ease of configuration, and with a strong adsorption of molecules. It’s a new type SERS substrate coupling in multi-dimensional.In this peper we designed single etched silver(gold) nanowire and silver nano film-silver nanoparticles coupling system as new SERS platforms. Our work enriched the SERS substrate types and application of SERS.
Keywords/Search Tags:Surface-Enhanced Raman Spectroscopy (SERS), Surface Plasmons(SPs), Raman "hotspots", silver and gold nanostructures
PDF Full Text Request
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