Construction And Raman Enhancement Performance Of Nanostructured2D Rdered Arrays

Surface Enhanced Raman Scattering (SERS) has attracted extensive attention since itsdiscovery. Reasonable design and prepare high-quality SERS active substrates, that in order toexplain SERS mechanism and promote the practical application of SERS technology, nowhave become the hot topics in the research of SERS. Aiming at prepare large area SERSsubstrates through a simple and convenient method and then to explore the structure impacton performance of the sunbstrates. We prepared monodispersed silica nanosphere withdifferent diameters by St ber and seed-regrowth methods, constructed large areas of2Dorderly arrays with metheds of spin-coating and solvent volatilization respectively,investigated the SERS performance of our2D orderly arrays with benzenethoil as a Ramanprobe and the relationship between the structure focters (such as the shap, size and density ofthe unit in the orderly structure) and the performance of the substrates. Main results andconclusions in the thesis are as follows:(1) Construction and SERS performance of holes array structures Six kinds ofmonodispersed silica nanosphere with different diameters (100-500nm) was prepared byseed-regrowth method. Closely packed (CP) silica nanosphere arrays were obtained after theself-assembly by solvent volatilization, and then filling the arrays with the polymerizedmonomer SR454HP, after in situ polymerization using UV irradiation, silica-polymercomposite templates were fabricated. The inverse opal structures emerged after the silicananospheres in the template being etched by HF aqueous solution. By subsequent depositionof Au layer, the metallic nanovoids array could be used as SERS active substrates. The SERSperformance of the obtained substrates has been explored using benzenethiol as the Ramanprobe. The substrates have obvious Raman enhancement effect; The hole size in the substratesurface can be modified by changing the silica diameter in the template, and with the increaseof hole size in the substrate surface, the SERS effect is enhanced accordingly.(2) Construction and structure mondification of the substrates with spherical protrusionsarrays A facile and scalable fabrication method of SERS active substrates with large area(81cm2) has been achieved by means of programmed spin-coating, in situ polymerization andmetallic deposition. The substrates have periodic hexagonal array of spherical protrusions.The surface structure of the fabricated substrates is featured as a hierarchical structure ofspherical protrusions array in long-range combine with island-like metallic film in short-range.The SERS performance of the obtained substrates has been explored using benzenethiol as theRaman probe. The SERS enhancement factors (EF) achieved in the order of107-108onaverage. The mean relative standard deviation (RSD) of EF was in the range of16%to35% which indicates the reproducibility of the substrates is excellent. The surface density and thepatterning periodicity of spherical protrusion on the substrate surface can be modified bychanging the type of precursor polymer monomers.Along with the surface density and thedensity and patterning periodicity of spherical protrusion increasing, both the Ramanenhancement facor and the reproducibility of the substrate definitely increase (the values ofEF increase and the RSD of EF decrease, repectively).(3) Construction and SERS performance of voids array structures A non-close packed(NCP) colloidal SiO2-array was fabricated by programmed spin-coating and in situpolymerization. The colloidal SiO2arrays are embedded in a polymer matrix, and the spheresof the top layer protrude out of the film, forming a periodic surface. After the first layer ofSiO2microspheres in the template being etched by HF aqueous solution, leaving behind ahighly periodic hexagonal array of polymer nanovoids. By subsequent deposition of Cr andAu layer, A highly periodic array of nanosized voids with large area (182cm2) has beenachieved, the metallic nanovoids array could be used as SERS active substrates withultra-sensitivity and excellent reproducibility. The SERS performance of our nanovoids arraywas probed by benzenethoil. The SERS enhancement factor can be as high as in the order of108-109on average over182cm2. The RSD of EF is in the range of5.5%to8.6%over182cm2which indicates the reproducibility of the substrates is excellent.