Surface-enhanced Raman Scattering Study On The Composite Metal Nanoparticle

The assembly of nano-sized metal with functionalized molecules is a rapidly emerging field of great fundamental and practical interest due to the prospective applications in future nanoelectronic devices. The charge transfer properties of individual particles are dependent of the particle size and the distance between the particles. Importantly, the activation energy for the electron transfer between the particles can be varied by the structure of the interconnected molecules. On the other hand, recent progresses in surface-enhanced Raman spectroscopy (SERS) study have made single-molecule detection possible, which is considerably interesting for the communities of nanomaterials, analytical chemistry, and single-molecule spectroscopy.In this thesis, the main research works and the conclusions are as follows:Gold nanoparticles with stable nature and even radius were prepared, two-dimension-sub-monolayer gold nanostructure on ITO glass was built by self-assembly. Next, semi-conductor material CdS was deposited using electrochemical method. Under different conditions, CdS with different shape and optic nature was obtained. The conditions of obtained for even radius CdS nanoparticles were investigated.Surface-enhanced Raman scattering of p-aminothiophenol (PATP) and 4-mercaptopyridine (4-MPy) molecules adsorbed in Au@CdS/PATP/Ag and Au@CdS/4-Mpy/Ag molecular junctions assembled on indium-doped tin oxide electrode was investigated under near IR excitation. Contribution from chemical enhancement can be relatively amplified, due to the near IR excitation is far way from the surface plasmon resonance of the nanosized metal particles. For the Au@CdS /PATP/Ag and Au@CdS/4-Mpy/Ag molecular junction, the energy required for the charge transfer process is much lower.