红外光谱的煤精类文物材质判别方法

Study on the Method of Distinguishing the Material of Jet-Like Cultural Relics Based on Infrared Spectra

我国是世界上最早使用煤及煤精的国家之一,但对考古出土煤精文物的研究发现,煤精文物原材料的质地常常偏离宝石学中对有机宝石煤精的定义。在此提出“煤精类文物”的概念,将以往出土文物中如褐煤、烛煤等与煤精文物材质近似但不同的材料归至同一文化概念中。目前对于煤精类文物制品的科学研究仍存在较大空白,其中最为基础的材质种类判别也没有科学的判断方法。以陕西周原贺家墓地、陕西咸阳岩村墓地、新疆吐鲁番胜金店墓地、新疆伊犁吉仁台沟口遗址四个遗址出土的16件煤精制品和原料为研究对象,初步探索漫反射傅里叶变换红外光谱在出土煤精类文物成分分析中的应用。结果表明,不同遗址出土的煤精类文物的红外谱图有较为明显的不同,同一遗址出土的煤精类文物的红外谱图在特征波段具有相似性,不同遗址煤精类文物则差异明显。使用Norris二阶导数法对红外光谱进行处理,提高吸收峰分辨率,为精细研究提供信息,选择特殊红外光谱参数I=A_(820 cm^(-1))/A_(2870 cm^(-1))定量分析不同样品的红外光谱,结合静水称重得到的部分样品的密度信息,对出土的煤精类文物制品材质的煤化程度初步判断。结合红外光谱特征波数的强度进一步通过主成分分析解释煤精类文物的红外光谱信息,来自不同遗址的煤精类文物样品在主成分分析得分图中得到了良好的区分,并且可以与特殊红外光谱参数I判别的初步结论互相对应。验证了以漫反射傅里叶变换红外光谱为主的无损分析方法在煤精类文物材质判别中应用的可行性;若结合不同产地煤精矿样红外光谱,则可以为煤精类文物产地判别提供研究方法。

China is one of the earliest countries in the world to use coal and jet.However,during the research of unearthed jet cultural relics,it was found that the texture of raw materials of jet cultural relics sometimes deviated from the jet defined in Gemology.Thus,the concept of jet-like cultural relics is advanced in this paper to have jet,lignite,candle coal and other materials which have a similar texture with jet put into the same cultural concept.At present,there is still a large gap in the scientific research on jet-like cultural relics,among which there especially is no scientific judgment method for the most basic study of material type identification.In this paper,16 pieces of jet-like relics unearthed from Zhouyuan Hejia Cemetery in Shaanxi,Xianyang Yancun Cemetery in Shaanxi,Turpan Shengjindian Cemetery in Xinjiang,and YiliJirentaigoukou Site in Xinjiang are studied for exploring the application of diffuse reflectance Fourier transform infrared spectroscopy in the composition analysis method of jet-like cultural relics.It can be seen through the result of the infrared spectrum that spectrograms of jet-like relics unearthed from different sites are quite different,while spectrograms of jet-like relics from the same site are similar.The infrared spectra are processed by Norris second derivative method for improving the resolution of absorption peak,a special infrared index I=A_(820 cm^(-1))/A_(820 cm^(-1))was selected to have the infrared spectra quantitative analysis of different samples.Combined with the density data of some samples,the coalification degree of jet-like cultural relics can be judged preliminarily.Furthermore,the materials of jet-like relics from different sites could be distinguished by the result of principal component analysis,which is consistent with the judgement of the special infrared index.This paper verifies the feasibility of non-destructive analysis method based on the infrared spectrum in distinguishing materials of jet-like cultural relics.In addition,a research method for the identification of jet-like cultural relics’origin can be provided if enough infrared spectrum of jet ore samples are collected from different areas.