Non-destructive detection of chemicals by scattering and fingerprinting in the THz band

In this paper, we show that the non-destructive detection of chemicals hidden in envelopes can be achieved using terahertz radiation in a simple two-step procedure: first, scattering of the terahertz waves is an indicator of the presence of powders in the envelope; second, the identification of the chemicals is done by spectral fingerprinting.