Absorption coefficients of selected explosives and related compounds in the range of 0.1-2.8 THz

Abstract

We have investigated the absorption spectra of seventeen explosives and related compounds (ERCs) by using terahertz time-domain spectroscopy in the 0.1-2.8 THz region. Most of these substances show characteristic absorption features in this frequency range. The measured absorption coefficients of these ERCs form a database, which is of great importance for biochemical, defense and security related applications.

Compound Explosives Detection and Component Analysis via Terahertz Time-Domain Spectroscopy

“…The characteristic peaks in the absorbance spectra of PETN, RDX, and TNT reported in previous literature [12] and those obtained by the WPSET and the truncating method are provided for direct comparison in Table 2. From Table 2 and Fig.…”

“…Furthermore, recent developments in THz technologies [6,7] showed that THz waves could be a strong candidate for overcoming the obstacles associated with conventional explosives detection technologies, leading to extensive applications in security and military-related fields [7][8][9][10]. It should be noted that THz time-domain spectroscopy (THz-TDS) has been heavily utilized as the workhorse of the investigation of these capabilities of the THz regime, including the works on the detection and identification of both exposed and covered explosives through diffuse reflectance [11], investigation of the absorption spectra of numerous explosives and related compounds [12], and establishment of new spectral features within the frequency region of 3-6 THz [13,14]. Unfortunately, raw THz data obtained from THz-TDS cannot always be used for direct explosives detection applications.…”

Transmission and Reflection Terahertz Spectroscopy of Insensitive Melt-Cast High-Explosive Materials

“…One of the driving forces behind the development of the terahertz technique (the spectral range from 0.1 to 10 THz) is the fact that many commonly used explosive materials (such as RDX, PETN, HMX, TNT and NQ) have unique spectral features in this range of radiation [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Moreover, non-polar dielectric materials (such as clothes, paper and plastics) are relatively transparent in the range up to about 3 THz [6,9], which raises hope of efficient identification of explosive materials remaining under cover or being inside packaging [6,12]. Spectral examinations are mostly carried out by means of time domain spectroscopy (TDS) [6-11, 13, 17-19], Fourier spectrometry [10] and the use of a tunable source and broadband detector [12].…”

“…This peak is crucial for its identification and is accompanied by a few other less clear peaks over higher frequencies [6-8, 10, 11, 13]. NQ has been quite well described in the literature as well-it has strong absorption peaks at 1.43, 2.38 and 2.76 THz [6]. In contrast, DNAN has only been briefly characterized [20].…”

“…The commonly used transmission configuration [6-8, 13, 16] gives clearly visible absorption peaks that may later be used as the basis for the identification of explosive materials. With regard to quite big attenuation (∼100-300 cm −1 ) [6], practical applications are limited to rare situations such as measurements of the thin layer of the powder placed in the envelope. For this reason, all samples prepared to transmission measurements are in the form of pressed pellets consisting of material with good transmission in the terahertz range (such as polyethylene) with suspended explosive material particles with a concentration of 5-20 %, which allows for proper determination of absorption characteristics [6] but ensures sufficient transparency.…”