Science Applications International Corporation, Gunpowder Branch, Aberdeen Proving Ground, Maryland 21010-5424, USA.
Appl Spectrosc. 2012 Jun;66(6):628-35. doi: 10.1366/12-06608.
The United States Army and the first responder community are evaluating optical detection systems for the trace detection of hazardous energetic materials. Fielded detection systems must be evaluated with the appropriate material concentrations to accurately identify the residue in theater. Trace levels of energetic materials have been observed in mutable polymorphic phases and, therefore, the systems being evaluated must be able to detect and accurately identify variant sample phases observed in spectral data. In this work, we report on the novel application of drop-on-demand technology for the fabrication of standardized trace 1,3,5-trinitro-1,3,5-triazine (RDX) samples. The drop-on-demand sample fabrication technique is compared both visually and spectrally to the more commonly used drop-and-dry technique. As the drop-on-demand technique allows for the fabrication of trace level hazard materials, concerted efforts focused on characterization of the polymorphic phase changes observed with low concentrations of RDX commonly used in drop-on-demand processing. This information is important when evaluating optical detection technologies using samples prepared with a drop-on-demand inkjet system, as the technology may be "trained" to detect the common bulk α phase of the explosive based on its spectral features but fall short in positively detecting a trace quantity of RDX (β-phase). We report the polymorphic shifts observed between α- and β-phases of this energetic material and discuss the conditions leading to the favoring of one phase over the other.
美国陆军和第一响应者社区正在评估用于痕量检测危险能 源材料的光学检测系统。现场部署的检测系统必须用适当的材料浓度进行评估，以准确识别战区中的残留物。已经观察到能 源材料在易变多晶相中存在痕量，因此，正在评估的系统必须能够检测和准确识别光谱数据中观察到的变体样品相。在这项工作中，我们报告了按需滴加工 艺在痕量 1,3,5-三硝基-1,3,5-三嗪（RDX）样品制备中的新应用。与更常用的滴加和干燥技术相比，按需滴加工艺在视觉和光谱上都进行了比较。由于按需滴加工艺可用于制造痕量危险材料，因此集中精力研究了在常用的按需滴加工艺中痕量 RDX 浓度下观察到的多晶相变化的特征。当使用按需喷墨系统制备的样品评估光学检测技术时，这些信息很重要，因为该技术可能会根据其光谱特征“训练”来检测爆炸物的常见块状α相，但在检测痕量 RDX（β相）时却未能准确检测到。我们报告了这种能 源材料的α相和β相之间观察到的多晶相转变，并讨论了导致一种相优先于另一种相的条件。
