Two Ways To Fabricate Ordered Thin Films & Their SERS Study

Colloids and latexes have been attracting considerable attention for their importance in the fields of colloidal science, chemistry, material sciences and biology in the modern science and technology. Especially, colloidal particles and their self-assembled systems have recently been an important and hot point in the colloid sciences. As an important aspect, the formation and utilization of highly ordered structures (photonic crystals and colloidal crystals) resulted from the self-assembly of monodispersed colloidal particles have been an intriguing subject of researches over the past several decades.In this thesis, the classical emulsion polymerization was employed to prepare the well monodispersed polystyrene colloidal microspheres. Through controlling the composition of reactants precisely, we can synthesize polystyrene microspheres with deferent diameter range from 300 nm to 1050 nm. The self-assembly property of these micropheres on vapor-liquid interface was studied and a surfactant-free LB method was invented. Some effect aspects such as particles hydrophobic property, surface pressure, substrates morphology and surface property were investigated. The particles hydrophobic property is the key for this self-assembly procedure. A thermo-rheology treatment was employed in order to improve particles surface hydrophobic property, a more ordered structure was obtained. This is an effective way to prepare two dimensional colloidal crystal templates, as well as paves the way to fabricate surface patterns based on these templates.Inspire from the principle of templates, we studied the thermo evaporation method using polystyrene colloidal crystal monolayer templates. This is a simple and effective way to fabricate periodic quasi-triangular island nanoarrays. The Surface Enhanced Raman Scattering (SERS) property using these patterned substrates was studied. As a result, patterned structure has more enhancing ability than the normal thermo evaporation silver films. It is because that the patterned structure has more edges and corners which can produce tremendous enhanced electromagnetic field. The silver film covered template also has more enhancing ability than the normal thermo evaporation silver films. The rational explanation is that it has more roughness surface.The layer-by-layer (LbL) self-assembly technique was combined with the template method for producing patterned structures. Noble metal colloid was employed as building blocks. We can get two kind of patterned surface: (i) on the template surface; (ii) on the surface of the substrates. If small metal nanopartcles were used, we can get patterned structures both on the template surface and on the surface of the substrates. If big metal nanopartcles were used, we can get patterned structures only on the template surface. No metal nanoparticles could be assembled on the the surface of the substrates, only polyelectrolyte films were"lithographied"by templates. Multilayers could be fabricated by repeating the assembling procedure. Using the patterned surface as secondary substrates, we achieve the compound self-assembly. More complicated structures have stronger Surface Plasma Resonance (SPR) coupling. It can detect 10-11 mol/L R6G solution. The techniques for the desired arrays and patterns and their corresponding applications in the broad fields will drive the further extension and intersect between the sciences of chemistry, physics, and biology and so on.As another kind of SERS substrates, semiconductor nanomaterials were prepared using a vapor deposition system. Lots of nanostructures of ZnO or Zn such as nanorod, nanowire, microcube and nanowall etc were synthesized. Some effect aspects such as catalyst center, pressure, composition were studied and discussed. The SERS property of these structures were investigated and the chemical enhance theory was supported.