Dielectric Characteristic Properties of Premium High-Energy Materials in the Terahertz Spectral Region

This paper presents a detailed investigation of the dielectric properties of four premium high-energy materials, namely RDX, HMX, TNT, and PETN, in the THz spectral region. A transmission-mode THz-TDS system was employed to determine the dielectric response of these explosives. The analysed results revealed that, similar to the absorption characteristics, the dielectric responses also exhibit distinct spectral features, with characteristic resonance peaks at 0.82, 1.36, 1.95, and 2.19 THz for RDX; 1.78, 2.51, and 2.91 THz for HMX; 1.66 and 2.2 THz for TNT; and 1.9 THz with a broad resonance around 2.7 THz for PETN. In addition to dielectric properties, we have further investigated the loss tangent factor and dielectric contrast between the investigated HEM samples, where RDX exhibited a pronounced dielectric loss peak near 0.8 THz, PETN showed a well-resolved maximum around 2.0 THz, and the RDX–HMX pair demonstrated strong dielectric contrast near 0.7–0.8 THz, revealing distinct material-specific spectral fingerprints and enhanced differentiation capability among explosive compounds through frequency-selective dielectric variations. These experimentally determined dielectric signatures confirm the material-specific behaviour in the THz regime. The findings demonstrate the strong capability of THz-TDS as a selective, rapid, and non-destructive technique for the identification and characterization of high-energy materials.