Terahertz spectroscopy of explosive materials

Shen, Yaochun; Taday, Philip F.; Kemp, Michael

doi:10.1117/12.577188

Cited by 30 publications

(14 citation statements)

References 6 publications

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“…The PC2 is orthogonal the third principal component (PC3) and interprets more information than PC3, and so forth. By plotting the scores of PCA, one can view interrelationships among samples, and detect and explain sample patterns, classifications, similarities or differences (Shen et al, 2004;Burnett et al, 2009). In this study, the SPSS (version 18.0, International Business Machines Corp., Armonk, NY, USA) statistical analysis software was used to perform the PCA.…”

Section: Principal Component Analysismentioning

confidence: 99%

Classification and recognition of genetically modified organisms by chemometrics methods using terahertz spectroscopy

Chen

Yin

et al. 2015

Int J of Food Sci Tech

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Summary The aim of this study was to evaluate the potential of terahertz (THz) spectroscopy to discriminate genetically modified (GM) and non‐GM organisms. In this study, eighty‐four sugar beet samples (thirty‐six GM sugar beets and forty‐eight of their parents, non‐GM ones) were investigated using terahertz time‐domain spectroscopy (THz‐TDS) system between 0.2 and 1.2 THz. Discriminant analysis (DA) based on principal component analysis (PCA) was used to discriminate sugar beet samples into two classes: GM organisms (GMOs) and non‐GMOs. Study results indicate that the DA method leads to an excellent classification. A total of 95.8% of the non‐GM samples were accurately classified, and no GM samples were misclassified, as there was 100% correctness. Results of this study demonstrate that THz spectroscopy combined with chemometrics techniques can provide a fast, nondestructive and reliable method to differentiate GMOs and non‐GMOs, which avoids time‐consuming, laborious and expensive sensory and chemical analyses.

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Section: Principal Component Analysismentioning

confidence: 99%

Classification and recognition of genetically modified organisms by chemometrics methods using terahertz spectroscopy

Chen

Yin

et al. 2015

Int J of Food Sci Tech

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“…A TPS spectra 3000 spectrometer (TeraView Ltd, Cambridge, UK; http://www.teraview.com) (22), with a spectral resolution of 0.036 THz over the range 0.1 to 3 THz, was used for the THz pulsed spectroscopy measurements. The samples were measured in the very stable fast-scan mode, which allowed 30 measurements to be performed per second.…”

Section: Measurementsmentioning

confidence: 99%

Feasibility of Using Terahertz Spectroscopy To Detect Seven Different Pesticides in Wheat Flour

Maeng

Baek

Kim

et al. 2014

Journal of Food Protection

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This study investigated the feasibility of detecting pesticides using terahertz (THz) spectroscopy in high-density polyethylene and/or wheat flour mixtures. The absorption spectra of seven pesticides (dicofol, chlorpyrifos, chlorpyrifos-methyl, daminozide, imidacloprid, diethyldithiocarbamate, and dimethyldithiocarbamate) were measured in the frequency range 0.1 to 3 THz at room temperature. Five of the seven pesticides exhibited specific absorption peaks in the low-energy THz range. The two remaining pesticides had no specific absorption peaks in this frequency range, but they exhibited different frequency-dependent refractive indices. The absorption coefficients of imidacloprid increased with its increasing weight ratio in high-density polyethylene, and the fitted power absorptions and refractive indices using a Maxwell-Garnett effective medium model were comparable to the measured data. Imidacloprid was also identified from its characteristic absorption peaks in wheat flour mixtures, and a linear relationship between the absorption coefficient and the weight ratio was observed. Our results show the potential of detection of selected pesticides in foods, such as wheat flour, using THz spectroscopy.

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“…However, from the time-domain terahertz image alone specific areas cannot be identified as lactose or explosive. Figures 4(b) and 4(c) show chemical mapping terahertz images obtained using component spatial pattern analysis based on the spectral fingerprints of lactose and RDX [14,16]. The lactose pellet and piece of RDX explosive are clearly detected, located, and identified.…”

Section: Detection and Identification Of Explosivementioning

confidence: 99%

“…This suggests that PCA should be a very efficient tool for analysing TPI data. We developed a PCA algorithm to analyze TPI data [14] and found that the TPI data can be compressed dramatically whilst retaining most essential information on layer thickness and interface quality. As an example, Figure 3 shows the results of comparison of the layer thickness results obtained by analyzing the original TPI data and the compressed data.…”

Section: Principal Component Analysis For Data Compressionmentioning

confidence: 99%

“…The terahertz waveforms, which contain vital information about the refractive indices of the layered structures, have been previously used for nondestructive analysis of tablet coating thickness [12] and for the clinical imaging of basal-cell skin carcinoma ex vivo and in vivo [13]. Terahertz spectral data have also been analyzed for chemical mapping of heterogeneous mixtures and for detecting and identifying explosive [14]. In this paper, we show that combining analysis of both time-domain and frequency domain TPI data gives a true 3D chemical mapping of a sample.…”

Section: Introductionmentioning

confidence: 99%

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3D chemical mapping using terahertz pulsed imaging

et al. 2005

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We report the use of a terahertz pulsed imaging technique for three-dimensional chemical mapping. Terahertz radiation reflected from a sample was measured pixel-by-pixel in time domain using a terahertz pulsed imaging system developed at TeraView Ltd, UK. The recorded terahertz waveforms were then transformed into frequency domain using time-partitioned Fourier transform. Structural maps of samples were obtained by analyzing the terahertz time-domain data whilst chemical maps were obtained from terahertz spectral data sets. For a sample comprising chemical A at the surface of a polyethylene pellet and chemical B buried inside the pellet, we have separated the component spatial patterns of the two chemicals using their spectral fingerprints. The reconstructed three-dimensional chemical maps not only locate the chemicals in the object, but also identify each chemical. We also demonstrate the capabilities of terahertz pulsed imaging for non-destructive analysis of coating thickness and quality, and for detecting and identifying explosive materials such as RDX.

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Terahertz spectroscopy of explosive materials

Cited by 30 publications

References 6 publications

Classification and recognition of genetically modified organisms by chemometrics methods using terahertz spectroscopy

Classification and recognition of genetically modified organisms by chemometrics methods using terahertz spectroscopy

Feasibility of Using Terahertz Spectroscopy To Detect Seven Different Pesticides in Wheat Flour

3D chemical mapping using terahertz pulsed imaging

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