초록 ▼

The excitation of the target nitrocompound with ultraviolet radiation ress in photodissociation yielding vibrationally excited NO with significant population of the v"=1 and v"=2 levels of the ground electronic state. As the population distribution of ambient NO favors the v"=0 level, discrimination

The excitation of the target nitrocompound with ultraviolet radiation ress in photodissociation yielding vibrationally excited NO with significant population of the v"=1 and v"=2 levels of the ground electronic state. As the population distribution of ambient NO favors the v"=0 level, discrimination between vibrationally excited NO and ambient NO is possible by probing the NO A-X (0,0),(1,1), and (2,2) bands near 226, 224, and 222 nm, respectively, employing (1+1) resonance-enhanced multiphoton ionization (REMPI). Many complex nitrocompounds cannot be photolyzed near 452 nm since their absorption cross sections are relatively small. Thus, the visible laser radiation is used to facilitate the detection of ambient NO and NO from NO.sub.2 by (2+2) REMPI and to discriminate these species from more complex nitrocompound analytes. The analytical utility of the present invention has been demonstrated at several photolysis/ionization wavelengths for NO/CH.sub.3 NO.sub.2 and NO.sub.2 /CH.sub.3 NO.sub.2 mixtures. Limits of detection have also been determined for NO, NO.sub.2, nitromethane (CH.sub.3 NO.sub.2), nitrobenzene (C.sub.6 H.sub.5 NO.sub.2) diethylglycoldinitramine (DEDGN), and trinitrotoluene (TNT), and are in the ppb to ppm range.

대표청구항 ▼

[ What is claimed is:] [1.] A sensor for detecting and discriminating NO and NO.sub.2 from more complex nitrocompounds in a sample in real-time and in situ, said sensor comprising:(a) pulsed laser means emitting three different wavelength laser beams, all of said laser beams having wavelengths in th

[ What is claimed is:] [1.] A sensor for detecting and discriminating NO and NO.sub.2 from more complex nitrocompounds in a sample in real-time and in situ, said sensor comprising:(a) pulsed laser means emitting three different wavelength laser beams, all of said laser beams having wavelengths in the visible or ultraviolet regions with at least one beam from each region, said beams producing ions from the sample;(b) detecting means for detecting the ions to produce a detection signal; and(c) data acquisition and analysis means receiving said detection signal for determining and discriminating a presence and a concentration of the NO, NO.sub.2 and nitrocompounds in the sample.