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  • Online Resource  (3)
  • Wai, Chien M.  (3)
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  • Online Resource  (3)
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  • 1
    Online Resource
    Online Resource
    SAGE Publications ; 2006
    In:  Applied Spectroscopy Vol. 60, No. 9 ( 2006-09), p. 958-963
    In: Applied Spectroscopy, SAGE Publications, Vol. 60, No. 9 ( 2006-09), p. 958-963
    Abstract: Nitroaromatics (such as dinitrotoluene, trinitrotoluene, and nitrobenzene) found in explosive vapors from buried landmines can be reduced to aminoaromatics by a novel process involving Pd metal nanocatalysts prepared in supercritical fluid carbon dioxide and supported on multi-walled carbon nanotubes. These aminoaromatics are fluorescent and, if desired, the fluorescence yield can be increased and the fluorescence maxima shifted further toward the red by reaction with appropriate derivatizing agents such as fluorescamine. Corrected spectra for these chemicals and their derivatives are included. Subpicomolar detection limits have already been achieved using a laboratory spectrofluorometer with a 150 W Xe arc lamp. Using lasers as excitation sources, this approach has the potential for developing a field sensor competitive with other methods currently used for detecting explosive vapors from land mines.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
    detail.hit.zdb_id: 1474251-2
    SSG: 11
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    SAGE Publications ; 2008
    In:  Applied Spectroscopy Vol. 62, No. 7 ( 2008-07), p. 739-746
    In: Applied Spectroscopy, SAGE Publications, Vol. 62, No. 7 ( 2008-07), p. 739-746
    Abstract: The detection and identification of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), and pentaerythritol tetranitrate (PETN) vapors have proven to be difficult and challenging due to the low vapor pressures of these high explosives. Detecting higher vapor pressure impurity compounds found in TNT and possible tagging agents mandated to be added to plastic explosives (RDX and PETN) would allow for easier vapor detection. The higher vapor pressure nitro compounds of interest are considered to be non-fluorescent; however, once reduced to their amino analogs, they have relatively high quantum yields. The standard reduction products, the reduction products obtained in solution, and the reduction products obtained in vapor phase were analyzed by conventional fluorescence, synchronous luminescence, and derivative spectroscopy. The nitro analogs of the isomers 1,3-diaminobenzene, 1,2-diaminobenzene, and 1,4-diaminobenzene are found as impurities in TNT. We provide for the first time the synchronous luminescence derivative spectra of these isomers; including their individual spectra and a spectrum of an isomeric mixture of the three. Using the standard reduction products associated with these isomers and other aromatic amines, our data suggest that the vapors of two signature impurities, 1,3-dinitrobenzene and 2,4-dinitrotoluene (2,4-DNT), minor impurity compounds, and two possible tagging agents, 2-nitrotoluene (2-NT) and 4-nitrotoluene (4-NT), can be detected and selectively identified using our fluorescence approach. To prove our methodology, we show that we were able to generate, collect, and reduce 2-NT, 4-NT, and 2,4-DNT vapors to their amino analogs. Using our fluorescence approach, these vapors could be detected and selectively identified both individually and in a mixture. Collectively, our data indicate that our method of detecting and identifying higher vapor pressure explosive-like compounds could potentially be used to detect and identify low vapor pressure explosives such as TNT, RDX, and PETN.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2008
    detail.hit.zdb_id: 1474251-2
    SSG: 11
    Location Call Number Limitation Availability
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  • 3
    In: Applied Spectroscopy, SAGE Publications, Vol. 61, No. 1 ( 2007-01), p. 68-73
    Abstract: The detection of explosive material is at the forefront of current analytical problems. A detection method is desired that is not restricted to detecting only explosive materials, but is also capable of identifying the origin and type of explosive. It is essential that a detection method have the selectivity to distinguish among compounds in a mixture of explosives. The nitro compounds found in explosives have low fluorescent yields or are considered to be non-fluorescent; however, after reduction, the amino compounds exhibit relatively high fluorescence. We discuss how to increase selectivity of explosive detection using fluorescence; this includes synchronous luminescence and derivative spectroscopy with appropriate smoothing. By implementing synchronous luminescence and derivative spectroscopy, we were able to resolve the reduction products of one major TNT-based explosive compound, 2,4-diaminotoluene, and the reduction products of other minor TNT-based explosives in a mixture. We also report for the first time the quantum yields of these important compounds. Relative quantum yields are useful in establishing relative fluorescence intensities and are an important spectroscopic measurement of molecules. Our approach allows for rapid, sensitive, and selective detection with the discrimination necessary to distinguish among various explosives.
    Type of Medium: Online Resource
    ISSN: 0003-7028 , 1943-3530
    RVK:
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2007
    detail.hit.zdb_id: 1474251-2
    SSG: 11
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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