Explosives Terahertz Spectroscopy

Terahertz (THz, 1THz=1012Hz) wave band is from 0.1THz to 10THz. It lies between millimeter and infrared waves. With its terahertz spectrum and imaging technology, we can get certain information of which is incapable by traditional method of microwave and X-ray. Rapid development of ultrafast laser in recent years provides stable light source for terahertz pulses generating and accelerates the application and researches for terahertz wave. Compared with Fourier Infrared Spectroscopy, detection technology of terahertz time-domain spectrum system has some advantages which are widely used in terahertz imaging and spectrum, such as insensitivity to thermal background, high signal-to-noise ratio and so on.In the first chapter of this letter, background of research,science and technology of generation and detection for terahertz wave are introduced. It specifies some security technology for nowadays and lists research status for explosive with terahertz detection in domestic and foreign countries. Our motivation and the signification for start this project was represented.The second chapter is mainly about terahertz time-domain spectrum system. Extraction method of related material parameters is explained.In the third chapter, results with terahertz detection of certain explosive are discussed, which include four kind of single compound explosive and nine kind of composite explosive. There are marked absorption peaks between 0.2 to 2.5THz for TNPG, PETN, HMX and RDX, and three of them agree with results in literature. In addition, terahertz spectrums of compound explosive of which mainly contains RDX and HMX are largely similar to their essential component individually. It indicates that terahertz spectrum technology has potential applications in identification and detection field for explosive.In the fourth chapter, spectrum of TNPG and PETN are analyzed theoretically. Terahertz spectrum, the basis of Quantum-Chemistry calculation and the introductions of Gaussian 03 and DMol3 software are presented, separately. Theoretical results of TNPG and PETN are highly accordant with our experiment results, separately. Additional, we discussed the method of intensity calculation for crystal cell of PETN.In the last chapter, we summarized our work of experiment and simulated results. Terahertz science and technology for explosive detection and its potential applications are discussed.