Chemistry: analytical and immunological testing – Nitrogen containing
Patent
1994-09-30
1998-03-17
Ludlow, Jan
Chemistry: analytical and immunological testing
Nitrogen containing
436110, 436116, 436153, 436172, 73 3514, 250282, 2504611, G01N 3322
Patent
active
057285845
ABSTRACT:
A method for the ultra-sensitive detection of atmospheric and surface adsorbed nitrocompounds such as propellants, explosives, and nitro-pollutants employs an excimer (ArF) laser operating at or near 193 nm to photofragment the target molecule and facilitate the detection of the characteristic NO fragment, formed from the dissociation of NO.sub.2, by resonance-enhanced multiphoton ionization (REMPI) and/or laser induced fluorescence (LIF) via its A-X, B-X, C-X, and/or D-X electronic transitions. In addition to NO, the detection of other fragments, such as C, CH, C.sub.2, NH and OH, by their ionization and/or prompt emission resulting from 193 nm excitation enhances the analyte identification. The analytical utility of this apparatus and method has been demonstrated on a number of compounds including dimethylnitramine (DMNA), nitromethane, nitrobenzene, orthonitrotoluene, para-nitrotoluene and trinitrotoluene (TNT). With the present system, limits of detection in the tens to hundreds of parts-per-billion (ppb) range have been achieved in the gas phase for all of these compounds, using only 1 mJ of laser energy at 193 nm.
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Lemire George W.
Sausa Rosario C.
Simeonsson Josef B.
Clohan Paul S.
Ludlow Jan
Roberto Muzio B.
The United States of America as represented by the Secretary of
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