Forensic applications of infrared chemical imaging: multi-layered paint chips.
Forensic applications of infrared chemical imaging: multi-layered paint chips.
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DOI：
10.1520/jfs2004502
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发表时间：
2005-05
影响因子：
1.6
通讯作者：
Katherine Flynn;R. O'Leary;C. Lennard;C. Roux;B. Reedy
中科院分区：
文献类型：
--
作者：
Katherine Flynn;R. O'Leary;C. Lennard;C. Roux;B. Reedy
本文探讨了红外化学（高光谱）成像技术作为一种法医分析技术的潜力，特别是汽车油漆芯片，以及一般的多组分（例如，分层）样品。详细介绍了改进的样品制备程序，用于油漆芯片的红外分析，建议在安装树脂与样品化学不相容的情况下，最好在软蜡中安装和切片，切片可以从软蜡中取出并压入KBr磁盘进行透射分析。多层涂料芯片的红外化学图像已经成功获得，与传统红外分析相比，其主要优势是在几分钟内收集整个样品的数千个红外光谱，空间分辨率约为5微米。与传统的红外光谱一样，化学物质可以从它们的光谱中识别出来，但也可以通过许多不同的方式提取丰富的可用信息，使两个样品之间的多组分光谱（因此化学）比较易于可视化和理解。在一种方法中，并排比较两个油漆芯片的红外化学图像可以被视为一个“电影”，其中每帧是两个样本在给定波数（频率）值下的强度图。在另一种方法中，图像文件中的光谱（像素）被分类为化学相似的组，从而产生“集群”图像，使同时比较两个油漆芯片中的所有层成为可能。这些方法适用于其他多组分样品，也适用于其他化学成像技术。
This paper examines the potential of infrared chemical (hyperspectral) imaging as a technique for the forensic analysis of automotive paint chips in particular, and multicomponent (e.g., layered) samples in general. Improved sample preparation procedures for the infrared analysis of paint chips are detailed, with the recommendation that where mounting resins are chemically incompatible with the sample, it is better to mount and section the sample in a soft wax from which the sections can be removed and pressed into a KBr disk for transmission analysis. Infrared chemical images of multilayered paint chips have been successfully obtained, with the chief advantage over conventional infrared analysis being that thousands of infrared spectra are collected in a few minutes across the whole sample, at a spatial resolution of around 5 microm. As with conventional infrared spectroscopy, chemical species can be identified from their spectra, but the wealth of information available can be also extracted in a number of different ways that make multicomponent spectral (and hence chemical) comparisons between two samples easy to visualize and understand. In one approach, the infrared chemical images of two paint chips being compared side-by-side can be viewed as a "movie," in which each frame is an intensity map of the two samples at a given wavenumber (frequency) value. In another approach, the spectra (pixels) in the image files are classified into chemically similar groups, resulting in a "cluster" image that makes it possible to simultaneously compare all of the layers in two paint chips. These methods are applicable to other multicomponent samples, and also to other chemical imaging techniques.