Terahertz Spectroscopy Of Illicit Drugs And Western Medicines

The terahertz (THz) radiation occupies a large portion of the electromagnetic spectrum between the microwave and infrared bands. Since it possesses many attractively characteristic properties, the studies of its application have caused more and more scientists' attentions. It is believed that THz technique has a good future in many different fields, such as physics, chemistry, biological medicine, communication, radar, security inspection, etc. In this thesis, some THz spectrum applications by studying the spectra of a few samples experimentally and theoretically were discussed.The main work of this thesis was proposed in chapter3 and chapter4.In chapter3, the spatial structures of methamphetamine and heroine were optimized and the lowest energy points were obtained by the density functional theory (DFT) with the packages of Gaussian03 software. The THz absorption frequencies of the two illicit drugs were calculated by the same basis and theory. The infrared spectra were compared between the experimental results measured by the THz time-domain spectroscopy and the theoretical results by the DFT calculations. Good agreements were got and the analysis of the spectra was tried with the help of Gaussian View 3.09. The THz collective vibration mode theory was further confirmed. The inspections of illicit drugs hidden in envelopes were made. The detections and identifications can be acquired by identifying the characteristic absorption peaks of illicit drugs.In chapter4, three amoxicillin capsules produced by three different companies were studied by the terahertz time-domain spectroscopy technique. The time-domain spectra and the frequency-domain spectra were obtained, and consequently both the absorption coefficient and the refraction index were calculated. The amoxicillin capsules produced by three companies could be separated by differentiating their absorption coefficient and refraction index. The results indicated that the terahertz time-domain spectroscopy would be a powerful candidate technique in the quality inspection of penicillin medicines and the strike of the faking drugs.The contents of the thesis were arranged as follows.Chapter1 was the introduction of this thesis.Chapter2 introduced the time-domain spectroscopy (THz-TDS) and the theoretical...