Rapid quantitative mineral and phase analysis using automated scanning electron microscopy (QemSCAN); potential applications in forensic geoscience
Rapid quantitative mineral and phase analysis using automated scanning electron microscopy (QemSCAN); potential applications in forensic geoscience
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使用自动扫描电子显微镜 (QemSCAN) 进行快速定量矿物和物相分析；
DOI：
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发表时间：
2004
期刊：
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通讯作者：
G. Miller
中科院分区：
文献类型：
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作者：
D. Pirrie;A. R. Butcher;M. Power;P. Gottlieb;G. Miller
QEMSCAN是一种扫描电子显微镜(SEM)系统，最初的设计目的是通过提供快速的自动化定量矿物分析来支持采矿业。该系统基于卡尔蔡司扫描电子显微镜，配备了最多四个轻元素能量色散X射线光谱仪。代表性的样品被安装在树脂或蜡块中，并在分析前抛光，或者可以安装在碳带上。在分析过程中，以用户定义的像素间隔收集X射线光谱，并非常快速地获取(每像素约10毫秒)。测量的光谱被自动与已知光谱的数据库进行比较，并且QEMSCAN计算机软件程序将矿物或相名称分配给每个测量点。通过这种方式，系统地绘制了每个颗粒的近表面定性元素组成图，并将其分配给矿物名称或化合物/物种，并创建了每个颗粒的数字像素地图。根据一系列参数，包括粒子大小和用户定义的像素间距(可以在0.2μm和25μm之间变化)，可以使用1μm像素间距每小时测量大约1,000个粒子，每个粒子的大小为1-10μm。除了提供每个颗粒的定性元素分析和矿物学或物相指定外，还生成与颗粒大小、形状和计算的比密度有关的数据。在这项研究中，通过分析(1)一系列土壤样本和(2)一系列工业园区的粉尘样本，评估了该自动化扫描电子显微镜系统在法医地学中的潜在应用。在这两个案例研究中，每个被分析样品的矿物学/物相组成都是不同的。此外，土壤样品的纹理数据和粉尘样品的颗粒形状数据表明，它们可以清晰地区分开来。使用QEMSCAN的自动扫描电子显微镜在法医案件工作中对土壤或其他微量证据的分析具有明显的潜在应用。
Abstract QemSCAN is a scanning electron microscope (SEM) system, initially designed to support the mining industry by providing rapid automated quantitative mineral analyses. The system is based upon Carl Zeiss SEMs fitted with up to four light-element energy dispersive X-ray spectrometers. Representative subsamples are mounted into either resin or wax blocks and polished prior to analysis, or can be mounted onto carbon tape. During analysis, X-ray spectra are collected at a user-defined pixel spacing and are acquired very rapidly (c. 10 ms per pixel). The measured spectra are automatically compared against a database of known spectra and a mineral or phase name is assigned to each measurement point by the QemSCAN computer software programs. In this way the near-surface qualitative elemental composition of each particle is systematically mapped, assigned to a mineral name or chemical compound/species, and digital pixel maps of each particle are created. Depending upon a range of parameters, including the particle size and the user-defined pixel spacing (which can vary between 0.20 μm and 25 μm), approximately 1000 particles, each 1–10 μm in size, can be measured per hour using a 1 μm pixel spacing. In addition to providing a qualitative elemental analysis and mineralogical or phase assignment for each particle, data relating to particle size, shape and calculated specific density are also generated. In this study, the potential application of this automated SEM system in forensic geoscience was evaluated by the analysis of: (1) a series of soil samples, and (2) a series of dust samples from an industrial complex. In both case studies, the mine-ralogy/phase composition of each sample analysed was found to be distinctive. In addition, textural data for the soil samples and particle shape data for the dust samples show that they can be clearly distinguished. Automated SEM using QemSCAN has clear potential application in the analysis of soil or other trace evidence in forensic case work.