Wu D, Singh J P, Yueh F Y, Monts D L
Appl Opt. 1996 Jul 20;35(21):3998-4003. doi: 10.1364/AO.35.003998.
Photofragmentation (PF) and subsequent nitric oxide (NO) laser-induced fluorescence (LIF) is being developed to measure the concentration of energetic materials (EM's) in soil and other media. Laser radiation near 226 nm photodissociates gas-phase EM to NO(2), which predissociates into NO that gives an intense luminescence. The EM concentration is inferred from the intensity of the NO fluorescence. We have studied the factors that affect the PF-LIF signal intensity, including the effect of buffer gas on the LIF spectrum of pure NO, the effect of 2,4,6-trinitrotoluene (TNT) pressure on the PF-LIF spectrum, the effect of buffer-gas pressure on the PF-LIF signal intensity of pure TNT, and the effect of temperature on the PF-LIF spectra of pure TNT and of TNT in simulated soil. Heating of the TNT sample above 343 K was found to increase the magnitude of the PF-LIF signal intensity significantly, but also was found to cause physical and chemical changes in the TNT sample. The effects of heating and evacuating on the TNT sample were investigated. TNT concentration calibration curves were obtained for TNT in simulated soil mixtures. The limit of detection of TNT in soil was estimated to be 40 parts in 10(9).
光致碎裂（PF）及随后的一氧化氮（NO）激光诱导荧光（LIF）技术正在被开发用于测量土壤及其他介质中含能材料（EM）的浓度。226nm附近的激光辐射将气相EM光解为NO₂，NO₂预解离为NO并发出强烈的荧光。EM浓度可通过NO荧光强度推断得出。我们研究了影响PF-LIF信号强度的因素，包括缓冲气体对纯NO的LIF光谱的影响、2,4,6-三硝基甲苯（TNT）压力对PF-LIF光谱的影响、缓冲气体压力对纯TNT的PF-LIF信号强度的影响以及温度对纯TNT和模拟土壤中TNT的PF-LIF光谱的影响。发现将TNT样品加热到343K以上会显著增加PF-LIF信号强度的大小，但也会导致TNT样品发生物理和化学变化。研究了加热和抽真空对TNT样品的影响。获得了模拟土壤混合物中TNT的浓度校准曲线。估计土壤中TNT的检测限为10⁹分之40。
