Diaz Daniel, Hahn David W
Mechanical & Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA.
Mechanical & Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA; College of Engineering, University of Arizona, Tucson, AZ, USA.
Spectrochim Acta A Mol Biomol Spectrosc. 2020 Jun 5;233:118204. doi: 10.1016/j.saa.2020.118204. Epub 2020 Feb 27.
Raman spectroscopy was evaluated as a sensor for detection of ammonium nitrate (NHNO, AN), fuel oil (FO), AN-water solutions, and AN- and FO-soil mixtures deposited on materials such as glass, synthetic fabric, cardboard and electrical tape to simulate field conditions of explosives detection. AN is an inorganic oxidizing salt that is commonly used in fertilizers and mining explosives, however, due to its widespread accessibility, AN-based explosives are also utilized for the manufacture of improvised explosive devices (IED). Pure AN crystals were ground to powder size and deposited on several substrates for Raman analysis, whereas FO was analysed in a quartz cuvette. To simulate field conditions samples of powdered AN, AN-water solutions (0.1% to 10.0% AN w/w), AN-soil (50% to 90% AN w/w) and FO-soil (50% to 75% FO w/w) were prepared and deposited on the clutter materials. Raman spectra were acquired at integration times between 0.1 and 30 s, and 3 replicate Raman measurements were carried out for each sample. The spectral window observed ranged from 300 to 3800 cm. Several characteristic Raman bands were found, namely, at 710 cm (NO) and 1040 cm (NO) for AN; 1440-1470 cm (CH) and 2800-3000 cm (CH) for FO; 3000-3500 cm (OH) for water; and 615 cm (CCl), 1254 cm (CH), 1400 cm (CH) and 1600 cm (aromatic ring) for polyvinyl chloride (PVC, electrical tape). The effect of the AN concentration and integration time on the total and net Raman intensities, relative standard deviation, signal-to-noise ratio and relative limit of detection was evaluated. The relative limit of detection of AN in water was 0.1% (1 mg/g), and absolute limit of detection was 1.0 μg. The optimum integration time (≈10 s) for the Raman sensor to capture the analyte signals was estimated based on the Raman figures of merit as a function of the integration time.
拉曼光谱被评估作为一种传感器，用于检测硝酸铵（NHNO，AN）、燃油（FO）、硝酸铵水溶液以及沉积在玻璃、合成纤维织物、硬纸板和电工胶带等材料上的硝酸铵与燃油和土壤的混合物，以模拟爆炸物检测的现场条件。硝酸铵是一种无机氧化盐，常用于肥料和采矿炸药中，然而，由于其广泛可得性，基于硝酸铵的炸药也被用于制造简易爆炸装置（IED）。将纯硝酸铵晶体研磨成粉末状并沉积在几种基质上进行拉曼分析，而燃油则在石英比色皿中进行分析。为了模拟现场条件，制备了硝酸铵粉末、硝酸铵水溶液（0.1%至10.0%硝酸铵重量/重量）、硝酸铵-土壤（50%至90%硝酸铵重量/重量）和燃油-土壤（50%至75%燃油重量/重量）的样品，并沉积在杂乱材料上。在0.1至30秒的积分时间内采集拉曼光谱，每个样品进行3次重复拉曼测量。观察到的光谱窗口范围为300至3800厘米。发现了几个特征拉曼谱带，即，硝酸铵在710厘米（NO）和1040厘米（NO）处；燃油在1440 - 1470厘米（CH）和2800 - 3000厘米（CH）处；水在3000 - 3500厘米（OH）处；聚氯乙烯（PVC，电工胶带）在615厘米（CCl）、1254厘米（CH）、1400厘米（CH）和1600厘米（芳香环）处。评估了硝酸铵浓度和积分时间对总拉曼强度和净拉曼强度、相对标准偏差、信噪比和相对检测限的影响。水中硝酸铵的相对检测限为0.1%（1毫克/克），绝对检测限为1.0微克。基于作为积分时间函数的拉曼品质因数，估算了拉曼传感器捕获分析物信号的最佳积分时间（约10秒）。
