The Study Of Raman Scattering On ZnO Thin Films And R6G Molecules

The Raman spectroscopy is a versatile technique in analyzing molecular structure. With the appearance of various new materials, the structural changes can activate intrinsic Raman modes that are normally forbidden or silent due to the breakdown of selection rules.With the development of near-field optical technique and the discovery of the surface-enhanced Raman scattering (SERS) effect, Raman spectrometer and near-field optical microscopy are combined to improve the spatial resolution of Raman spectrum and the ratio of signal to noise. Now a series of Raman spectrum application technology has come into being, and Raman scattering will be used extensively in biology, medicine, material and other fields.This thesis focuses on the application of Raman spectrum. We study the application of the micro-Raman scattering on material science and the application of the surface-enhanced Raman scattering on the high fluorescence molecules.Firstly, we study the micro-Raman scattering of ZnO thin films. Raman scattering can give information about the crystal structure on the scale of a few lattice constants. We study the structure characteristics and the phase composition of undoped ZnO thin films and doped ZnO thin films by means of Raman spectroscopy. The degree of crystallinity on the different substrates is analyzed according to the characteristic peak intensity.The stress is estimated according to the frequency shift of the characteristic peak, and the influence of the dopants on carrier concentration is also studied according to the A₁ (LO) mode.Secondly, we study the SERS of R6G. In order to obtain favorable surface enhancement, the appropriate substrate is important, so we synthesize the silver colloid by microwave method, which is used as the substrate in our SERS experiment. We obtain the SERS of R6G with high ratio of signal to noise. Compared with the conventional Raman spectrum, most of peaks are strengthened and some new bands are observed in the SERS of R6G. Based on electromagnetic mechanism and chemical mechanism, the enhancement reasons of those bands are explained.