Terahertz And Raman Spectroscopic Investigation Of Explosives And Carbon Monoxide

This thesis presents an overview of the detection technology of explosives and the research of gas sensing. Considering the importance of explosives detection in the field of security and the increasing atmospheric pollution, the research on Fourier-transform near infrared Raman spectroscopy (FT-NIR) and terahertz time-domain spectroscopy(THz-TDS) of explosives has been developed preliminarily. Besides, we have investigated the THz-TDS as a technique for gas sensing. Carbon monoxide has been chosen as a sample gas.We briefly summarize the Raman spectroscopy; analyze the main methods and technologies for THz generation, detection and THz technology, especially the THz-TDS. Then, we have been done the researches in two fields, explosive detection and gas sensing.In explosives detection, investigations on explosives have been done as follows:Firstly, the FT-NIR of explosives (TNT, 2, 4-DNT, HMX, RDX, HNIW) is obtained. The results are classified according to the molecular structure of the samples. We found that the spectra of structurally similar explosives samples are very similar. Raman shift of the common functional group in samples, such as the -NO2, is almost accordant.Secondly, the optical characteristics of 5 kinds of explosives are detected by THz-TDS under the condition filled with Nitrogen at room temperature. The absorption and dispersion spectrums are obtained based on the physical model represented by T. D. Dorney and L. D. Duvillaret to abstract the optical parameters of materials in THz range. The absorption peaks have the significant difference between the different samples. Comparing the spectrums of absorption and refractive index of the same sample, the relationship between absorption and dispersion is discussed and the Kundt Rule is validated in THz range.Finally, the FT-NIR and THz-TDS of the explosives have been combined to broaden the spectral characteristics of samples. Analyzed explosives spectral, the spectral peaks are obtained by the two technologies. While the Raman shift is almost similar for the structurally similar samples only in the intensity and peak position with a very small difference, such as TNT and 2, 4-DNT, the THz absorption spectra are significantly different.In gas sensing, investigations on carbon monoxide have been done as follows:We present the absorption spectra of carbon monoxide by THz-TDS in the frequency range...