ABSTRACT Cultural heritage objects present a special set of challenges to analyze chemically. Often micro-sampling or even contacting the object is not appropriate or deemed too risky for fragile surfaces. Fourier Transform Infrared (FTIR) spectroscopy is a commonly used analytical technique for organic compound identification, either in a micro-sampling or Attenuated Total Reflection (ATR) mode, both of which inherently require some measure of contact with the sample. Presented here is a case study of the use of specular reflection FTIR spectroscopy, an FTIR collection mode that allows positive chemical identifications in a non-sampling and non-contact way. Although this paper focuses on the case study of coatings on 19th century photographs, the specular reflection FTIR mode is applicable to surface coatings on any artifact where molecular composition identification is needed but micro-sampling or physical contact with the sample have been ruled out. The main limitation of the specular reflection mode has traditionally been the lack of specular reflection FTIR reference libraries. As a result, the analytical project presented here first required generation of a specular reflection FTIR spectral library for historical coating materials used on 19th century prints by creating modern reference samples. The project is a result of collaboration between conservators at the Weissman Preservation Center at Harvard Library and materials scientists at Harvard’s Center for Nanoscale Systems to analyze original coatings on 19th century salted paper photographs in the collection of the Harvard University Archives.

中文翻译：

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镜面反射FTIR：一种非接触方法，用于分析照片和其他文化材料上的涂层

摘要文化遗产物品提出了一系列特殊的化学分析挑战。通常，微采样甚至接触物体都是不合适的，或者对于脆弱的表面来说风险太大。傅里叶变换红外（FTIR）光谱是一种常用的分析技术，用于以微采样或衰减全反射（ATR）模式识别有机化合物，这两种方法本质上都需要某种程度的与样品接触的方法。这里介绍的是使用镜面反射FTIR光谱的案例研究，FTIR光谱是一种FTIR收集模式，允许以非采样和非接触方式进行阳性化学鉴定。尽管本文着重研究19世纪照片上涂料的案例研究，镜面反射FTIR模式适用于任何需要识别分子成分但已排除了微取样或与样品物理接触的人工制品上的表面涂层。传统上，镜面反射模式的主要限制是缺少镜面反射FTIR参考库。结果，这里介绍的分析项目首先需要通过创建现代参考样品来生成19世纪版画中使用的历史涂料的镜面反射FTIR光谱库。