Trends in microwave spectroscopy for the detection of chemical agents

Bousquet, Robert R.; Chu, Pamela M.; DaBell, Ryan S.; Grabow, Jens‐Uwe; Suenram, R. D.

doi:10.1109/jsen.2005.851000

Cited by 16 publications

(9 citation statements)

References 46 publications

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“…The linewidth (HWHM) of the individual components is on the order of 1.5 kHz, or 0.00000005 cm −1 ; at an appreciable S/N ratio a frequency accuracy of 150 Hz, or 0.000000005 cm −1 is achieved for unblended lines. The extraordinary resolution provides supersonic-jet expansion FT-MW spectroscopy with a chemical specificity unrivaled by any other analytical method (Suenram et al 1999, Bousquet et al 2005. Furthermore, the sensitivity allows for the observation of, e.g., mono-deuterated asymmetric-top molecules in natural abundance (Dreizler et al 1998).…”

Section: Supersonic-jet Short-stimulus Signalmentioning

confidence: 99%

Fourier Transform Microwave Spectroscopy Measurement and Instrumentation

Grabow

2011

Handbook of High‐resolution Spectroscopy

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Microwavemolecular spectroscopy is progressing impressively. In part, profiting from recent experimental developments that combine jet‐expansion sources with elaborate means for preparation of new chemical systems, advances in spectroscopic instrumentation — namely, the rise of very sensitive and high‐resolution time‐domain techniques — are even more significant. Precise structural studies have always been a strength of rotational spectroscopy; now problems arising from convoluted intramolecular dynamics, such as conformational, tautomeric equilibria, and other large amplitude motions, as well as intermolecular vibrational energy redistribution and isomerization, can be targeted with the unrivaled precision of rotational investigations. Numerous interesting chemical systems like molecules with multiple concurrent internal motions, larger complexes, aggregates, biomolecules, and transient species were characterized recently — positioning microwave spectroscopy today as a prime method for the investigation of multidimensional flexible systems. Rotational studies elucidate an extensive range of intermolecular interactions, ranging from hydrogen bonding and van der Waals interaction to the unusual effects observed in quantum solvation. The development of microwave pulsed excitation multiresonance techniques and the advent of instantaneous broadband‐coverage microwave spectroscopy are impressively boosting the capabilities of rotational spectroscopy to quite routinely disentangle the unique spectral signatures that encode the structure and dynamics of hitherto pathological molecular cases. The versatile capabilities of microwave coherence spectroscopy are outlined in the treatment of time‐dependent interaction of rotating molecules with radiation.

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Section: Supersonic-jet Short-stimulus Signalmentioning

confidence: 99%

Fourier Transform Microwave Spectroscopy Measurement and Instrumentation

Grabow

2011

Handbook of High‐resolution Spectroscopy

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“…Successful application of microwave spectroscopy to trace gas detection would require that reliable assignments of transition frequencies were available from laboratory studies beforehand. Bousquet et al (2005) have described efforts to adapt the techniques of microwave spectroscopy for the detection of chemical warfare agents.…”

Section: Emerging Themesmentioning

confidence: 99%

New opportunities and emerging themes of research in microwave spectroscopy

Walker

2007

Phil. Trans. R. Soc. A.

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It is easy to set a frisbee spinning but hard to flip a javelin end-over-end. The properties of a rotating body are determined by its moment of inertia. Changes in the energy associated with the rotation of a single molecule are incremental, or quantized, in contrast with the everyday examples of the frisbee and the javelin. Only photons with energies that correspond to specific discrete frequencies of electromagnetic radiation can be absorbed or emitted to cause transitions between different rotational energy levels. Photons that cause rotational transitions generally have microwave or millimetre-wave frequencies. Microwave spectroscopy thus provides a basis for exploring molecular structure through studies of molecular rotation. The first experiments involving microwave spectroscopy exploited technology developed for radio detection and ranging during the Second World War. Microwave spectroscopy is now being applied to study chemical reactions significant in atmospheric chemistry and to probe superfluidity in Hen clusters. This article reviews the research themes that were the focus of the past 50 years and surveys new opportunities.

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“…Other major tools for CWA detection include liquid chromatography and mass spectrometry [13], Raman spectroscopy [14], microwave spectroscopy [15], photoacoustic spectroscopy [16], and laser-induced break-down spectroscopy [17]. The latter spectroscopic methods are prone to the same problem as the IR spectroscopy of BWA, the mathematical problem of unmixing/deconvoluting of a signal from the mixture.…”

Section: Introductionmentioning

confidence: 99%

A rugged early-warning spectroscopic system for real-time environment water monitoring

Liu

Zeifman

2006

SPIE Proceedings

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The absorption spectra of BWA/CWA often heavily overlap with each other and with absorption spectra of harmless species. The traditional approach of spectral discrimination usually involves estimation of concentration of each constituent, wherein the first-and second derivatives are being used as the spectrum features and the linear relationship between these features and the concentrations is sought by, e.g., the partial least squares or principal component regression. These algorithms may not be suitable for real-time early warning detection of BWA/CWA in the gaseous/liquid environments, especially taking into account the inevitable presence of environmental constituents with unknown spectra. In this paper, we present a new approach suitable for ragged, real-time spectral discrimination. In this approach, we are using an independent component analysis (ICA) technique to unmix the mixture spectra into independent spectral components. In order to classify the components, we have developed a special feature extraction algorithm based on a complex wavelet transform. We have tested the procedure experimentally using a ragged fiberoptics spectrometer working in the NIR region (800 -1000 nm), and mixtures of organic liquids. The obtained results clearly demonstrate the applicability of the proposed system to the early warning "trigger"-type detection suitable for real-time environmental monitoring.

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Trends in microwave spectroscopy for the detection of chemical agents

Cited by 16 publications

References 46 publications

Fourier Transform Microwave Spectroscopy Measurement and Instrumentation

Fourier Transform Microwave Spectroscopy Measurement and Instrumentation

New opportunities and emerging themes of research in microwave spectroscopy

A rugged early-warning spectroscopic system for real-time environment water monitoring

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