THz transmittance and reflectance spectroscopy on security-relevant materials using synchrotron radiation

Many attempts have been made to introduce THz detection systems for security inspection at check points. For all approaches the spectral characteristics of the most common materials of investigation are required both in reflectance and transmittance. We investigated a broad variety of materials, including explosives, polymers and drugs by using Fourier-transfom spectroscopy and synchrotron radiation as a broadband THz source. In conclusion, we demonstrated that the transmission of 2 mm-thick pellets of pure explosive samples is vanishingly small in the 2-20 THz range, thus calling for reflection-based explosive detection devices for security application. We also observed that the optical constants of explosives strongly differ one from the other, indicating that substance-specific detection by terahertz radiation is possible.