红外差谱技术在交通事故物证比对中的应用研究

Application of IR Differential Spectrum Technology to Compare the Evidential Material in Traffic Accident

目的为认定交通事故中各车辆的法律责任,需要对案件相关的纤维、漆片等检材进行同一物证比对,然而,检材经常会受到灰尘、油渍和/或血液等杂质污染,这给物证比对带来干扰。红外差谱技术具有辨别混合物中不同成分的功能,因此,可将其应用于交通事故案件中受污染检材的鉴定。方法通过模拟交通事故现场,分别制备受机油和/或血液污染的纤维和漆片检材,利用傅里叶变换红外光谱仪对污染检材以及控制样品进行分析,借助红外差谱技术对红外谱图进行处理,排除污染物的干扰。结果处理后得到的谱图与控制样品的谱图进行比对,结果显示两者主要官能团吸收峰位置完全相同,峰形基本一致,各主要官能团在其吸收位置的峰强度也基本一致,可以出具比对一致的结论。结论无论检材是否受到污染,红外差谱技术都可为交通事故案件提供证据支持和/或参考。

Objective In order to verify the legal status of a car involving into one traffic accident, comparison is often required to conduct on the evidential materials such as the fibers, paint chips and the others related. However, the evidential materials are frequently polluted with dust, oil and/or blood, leading to difficulty of observing and identifying the relevant evidential materials. IR （infrared） differential spectrum technology can distinguish the kinds of materials through its differentiability into various substances, therefore, it should be also used for differentiation of the polluted evidential materials from traffic scene. Methods In this paper, the fibers and paint chips, polluted by engine oil and/or blood, were prepared to simulate the polluted evidential materials from traffic accident scene. Fourier transform infrared spectrometry was used to get the total spectrograms of both the prepared materials and control samples. Results By IR differential spectrum technology, the interference of pollutants was removed from the examined materials with subtraction of the corresponding constituent sample（s） from the total spectrogram. The resultant spectrograms were accordingly same as those of the unpolluted samples at the peak positions, basic peak shapes and peak intensities. Thus, a conclusion can be drawn that the polluted materials analyzed via IR differential spectrum technology are of identical to the unpolluted ones. Conclusions IR differential spectrum technology does assist in providing evidential support and/or reference for the involved traffic accident cases no matter whether the obtained evidential materials are polluted or not.