Surface Enhanced Raman Scattering Effects Of Nanoparticles In THz Region

Terahertz spectroscopy is located in the transition region between electronics based on the classical theory and photonics based on quantum theory, thus it has many special and superior performances. Terahertz waves have been successfully applied in many fields such as: medicine, imaging, communications and astronomy. Especially for its prominent superiorities on the detection of biological macromolecules, Terahertz technology is same as the surfaceenhanced Raman scattering(SERS). So the combination of the terahertz wave and the SERS detection techniques has a clear advantage in the detection of macromolecules, since the result can not only describe the molecular structure but also detect the concentration of molecules. The study of the surface electromagnetic enhancement of metal and semiconductor nanoparticles as the SERS substrates is the basis of the thesis proposition, and here, the numerically simulation of the surface electromagnetic enhancement is operated by the finitedifference time-domain(FDTD) methods. In this paper, the general contents of research on the combination of terahertz technology and SERS technology are as follows:1) Basic theory of SERS and Raman scattering. The principle of Raman scattering and the enhanced mechanism of SERS are analyzed. We perform an analysis for the enhanced mechanism of nanoparticles as SERS substrates, which is the foundation of the combination of Terahertz technology and SERS technique.2) Introduction of FDTD method and FDTD Solutions software. We describe the time domain differential forms of Maxwell equations illustrating electromagnetic fields and the set of FDTD Solutions software which is based on the finite-difference time-domain(FDTD) methods. And introduce the Drude model of dispersive medium like metal and semiconductor nanoparticles as SERS substrates in the terahertz range.3) The SERS effect of metal and semiconductor nanoparticles in the Thz range. The near field electromagnetic enhancement, and thus the SERS enhancement factor of metal and semiconductor nanoparticles in Thz regime are get by FDTD Solutions. In the paper, we conduct simulation experiments of gold and In Sb nanoparticles in ―hot spot‖ and the results indicate that SERS enhancement factor could up to 106 and 109, respectively.