THz-Wave Spectroscopy Applied to the Detection of Illicit Drugs in Mail

Dobroiu, Adrian; Sasaki, Yu; Sakamoto, Takayuki; Otani, Chiko; Kawase, Kodo

doi:10.1109/jproc.2007.898840

Cited by 47 publications

(33 citation statements)

References 13 publications

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“…THz spectroscopy has seen use in a number of applications, including the detection of illicit drugs, [1][2][3] explosives, [4][5][6] and crystal polymorphs in pharmaceutical research. [7,8] The value of THz spectroscopy stems from the low-energy vibrations present in solid-state compounds and molecules that form the basis of a spectral "fingerprint" usable for identification, detection, and characterization.…”

Section: Introductionmentioning

confidence: 99%

“…[9][10][11] To date, there has been limited work performed to gauge the applicability of THz spectroscopy as a tool for the detection and identification of concealed drugs, with the majority of the available work performed on illicit drugs and not drug precursors or related products. [2,3,12,13] The work presented here is of (1R,2S)-2-methylamino-1-phenylpropan-1-ol, (C 10 H 15 NO), more commonly known as (1R,2S)-(À)-ephedrine (ephedrine). The compound is a naturally occurring sympathomimetic amine, central nervous system stimulant, [14] and bronchodilator.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of (1R,2S)‐(−)‐Ephedrine by Cryogenic Terahertz Spectroscopy and Solid‐State Density Functional Theory

et al. 2009

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The terahertz (THz) spectrum of the pharmaceutical (1R,2S)-(-)-ephedrine from 8.0 to 100.0 cm(-1) is investigated at liquid-nitrogen (78.4 K) temperature. The spectrum exhibits several distinct features in this range that are characteristic of the crystal form of the compound. A complete structural analysis and vibrational assignment of the experimental spectrum is performed using solid-state density functional theory (DFT) and cryogenic single-crystal X-ray diffraction. Theoretical modeling of the compound includes an array of density functionals and basis sets with the final assignment of the THz spectrum performed at a PW91/6-311G(d,p) level of theory, which provides excellent solid-state simulation agreement with experiment. The solid-state analysis indicates that the seven experimental spectral features observed at low temperature consist of 13 IR-active vibrational modes. Of these modes, nine are external crystal vibrations and provide approximately 57% of the predicted spectral intensity. This study demonstrates that the THz spectra of complex pharmaceuticals may be well reproduced by solid-state DFT calculations and that inclusion of the crystalline environment is necessary for realistic and accurate simulations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of (1R,2S)‐(−)‐Ephedrine by Cryogenic Terahertz Spectroscopy and Solid‐State Density Functional Theory

et al. 2009

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“…These include the following: resonant tunnelling diodes, THz plasma-wave photomixers, THzquantum cascade lasers [25,26], and Bloch oscillators. Numerous types of THz detectors [20][21][22][23] for time-domain systems have been studied so far including: bolometers; singleelectron transistors; photoconductive antennas; and electro-optic sampling techniques for time-domain detection. THz waveguiding using conventional structures, such as plastic ribbons, metal tubes, and dielectric fibers has been demonstrated-however, these still have limited applications because of high losses.…”

Section: Introductionmentioning

confidence: 99%

Terahertz Josephson plasma waves in layered superconductors: spectrum, generation, nonlinear and quantum phenomena

et al. 2010

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The recent growing interest in terahertz (THz) and sub-THz science and technology is due to its many important applications in physics, astronomy, chemistry, biology, and medicine, including THz imaging, spectroscopy, tomography, medical diagnosis, health monitoring, environmental control, as well as chemical and biological identification. We review the problem of linear and nonlinear THz and sub-THz Josephson plasma waves in layered superconductors and their excitations produced by moving Josephson vortices. We start by discussing the coupled sine-Gordon equations for the gauge-invariant phase difference of the order parameter in the junctions, taking into account the effect of breaking the charge neutrality, and deriving the spectrum of Josephson plasma waves.We also review surface and waveguide Josephson plasma waves. The spectrum of these waves is presented, and their excitation is discussed. We review the propagation of weakly nonlinear Josephson plasma waves below the plasma frequency, ω J , which is very unusual for plasma-like excitations.In close analogy to nonlinear optics, these waves exhibit numerous remarkable features, including a self-focusing effect, and the pumping of weaker waves by a stronger one. In addition, an unusual stop-light phenomenon, when ∂ω/∂k ≈ 0, caused by both nonlinearity and dissipation, can be observed in the Josephson plasma waves. At frequencies above ω J , the current-phase nonlinearity can be used for transforming continuous sub-THz radiation into short, strongly amplified, pulses.We also present quantum effects in layered superconductors, specifically, the problem of quantum MQT -macroscopic quantum tunnelling.z-axis is directed across the layers; y-axis is directed along the magnetic field.4

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“…Consequently, the technological advances have been accompanied by much interest in possible applications of security [3][4][5], pharmaceutical [6][7], nondestructive testing (NDT) [8][9], drug inspection [10] and biological molecules testing [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Terahertz Absorption Spectra Characteristic of 1-Naphthaleneacetic Acid and 4-Chlorophenoxyacetic Acid in Terahertz Region

Wang

et al. 2012

2012 International Conference on Industrial Control and Electronics Engineering

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We firstly study terahertz time-domain spectroscopy (THz-TDS) characterization of two kinds of pesticides 1-naphthaleneacetic acid and 4-chlorophenoxyacetic acid. The absorption spectrum and refractive index of samples were measured. Theoretical investigation of the vibrational spectrum of pesticides was performed based on density function theory (DFT). We observed that experiment spectra are in rough qualitative agreement with these theory spectra. Its chemical composition was successfully identified through spectral analysis of the recorded terahertz waveform. These feature spectra measurements are helpful to form a database of pesticide.

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THz-Wave Spectroscopy Applied to the Detection of Illicit Drugs in Mail

Cited by 47 publications

References 13 publications

Investigation of (1R,2S)‐(−)‐Ephedrine by Cryogenic Terahertz Spectroscopy and Solid‐State Density Functional Theory

Investigation of (1R,2S)‐(−)‐Ephedrine by Cryogenic Terahertz Spectroscopy and Solid‐State Density Functional Theory

Terahertz Josephson plasma waves in layered superconductors: spectrum, generation, nonlinear and quantum phenomena

Analysis of Terahertz Absorption Spectra Characteristic of 1-Naphthaleneacetic Acid and 4-Chlorophenoxyacetic Acid in Terahertz Region

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