Non-Destructive High-Resolution X-ray Diffraction for Cultural Heritage

许多不同的分析技术通常用于对遗产物品进行科学分析，以阐明其物质特性。每种技术在所返回的信息类型、复杂性和费用、样品制备要求以及对不同类型实物的适用性方面都有其优缺点。虽然X射线荧光（XRF）在提供元素信息方面非常有用，并且傅里叶变换红外光谱和拉曼光谱等技术可以产生相信息，但只有X射线衍射（XRD）才能明确无误地识别晶体相。尽管如此，XRD在考古学中的应用相对分散，并且仅在利基领域有用，主要是因为样品制备要求。该项目旨在将非破坏性XRD技术的令人兴奋的进步带到文化遗产和考古文物的考古测量分析中。申请人开发的创新XRD方法能够对物体进行高分辨率XRD分析，而根本不需要样品制备。虽然二十年前对文物进行取样被认为是标准做法，但手持式XRF等非破坏性技术的发展使得博物馆和其他收藏品的馆长不太愿意允许侵入性程序。保持文物的物理完整性现在被认为是至关重要的。对某些类别的文物，破坏性取样是目前确定其来源的唯一现实办法。石制品是一个主要的例子。西方博物馆中的许多石制品来自艺术市场，许多人对其中的真实性表示怀疑。确定石制品来源的最有效方法是详细描述矿物成分，以确定地质来源，但目前几乎总是需要破坏性取样。第二个主要的应用领域是在美术绘画和绘画对象，如木乃伊肖像和印度微型颜料的识别。虽然拉曼光谱法可以成功地识别相当大比例的颜料，但仍有很大一部分颜料是该方法无效的。颜料具有独特的衍射图案指纹，XRD研究可以提供基本上所有颜料的关键信息。对石制文物和绘画及彩绘文物的研究将成为拟议项目的主要重点。目前，这种创新的XRD技术需要同步加速器设施来实现。申请人将在美国国家标准与技术研究所的原理验证实验中使用尖端的高分辨率X射线探测器（超导过渡边缘传感器阵列）来演示该方法。这项工作将支持该技术从同步加速器到实验室和博物馆的最终过渡。另一个目的是研究原型手持XRD仪器的考古能力，基于相同的基础技术，但分辨率低得多。以前使用这种原型设备的工作强烈表明，金属文物的分析是一个特别有前途的领域。避免从高价值和稀有物体中提取样品的需要是一个非常重要的优势，适用于其他研究领域。其中包括古生物学以及对样品返回任务带回地球的陨石和行星物质的研究。

Many different analytical techniques are commonly applied in the scientific analysis of heritage objects in order to elucidate their material properties. Each technique has advantages and disadvantages in terms of the type of information returned, complexity and expense, sample preparation requirements and applicability to different types of material objects. While X-ray fluorescence (XRF) is very useful in providing elemental information, and techniques such as Fourier-transform infrared spectroscopy and Raman spectroscopy can yield phase information, only X-ray diffraction (XRD) allows the definitive and unambiguous identification of crystallographic phases. Despite this, the use of XRD in archaeometry has been relatively sporadic and of utility only in niche areas, largely because of sample preparation requirements. This project aims to bring exciting advances in non-destructive XRD techniques to the archaeometric analysis of cultural heritage and archaeological artefacts. The innovative XRD methods developed by the applicants enable high resolution XRD analysis of objects with no sample preparation requirement at all. While twenty years ago sampling of artefacts was considered standard practice, the growth of non-destructive techniques such as handheld XRF have made curators at museums and other collections very much less willing to allow invasive procedures. Maintaining the physical integrity of heritage artefacts is now considered to be of paramount importance. There are certain classes of heritage objects for which destructive sampling is currently the only realistic approach to determining provenance. Stone artefacts are a primary example. Many stone objects in Western Museums are from the art market and doubts have been expressed about the authenticity of many. The most effective method of provenancing stone artefacts is the detailed characterisation of the mineralogical composition in order to identify the geological source, but destructive sampling is nearly always currently required for this purpose. A second major application area is the identification of pigments in fine art paintings and on painted objects such as mummy portraits and Indian miniatures. Although Raman spectroscopy can successfully identify a significant proportion of pigments, there remain an important number for which the method is ineffective. Pigments have unique diffraction pattern fingerprints and XRD studies can provide the critical information for essentially all pigments. The study of stone artefacts and of paintings and painted artefacts will form a major focus of the proposed project. Currently, this innovative XRD technique requires synchrotron facilities for implementation. The applicants will demonstrate the method using cutting-edge high-resolution X-ray detectors (superconducting transition-edge sensor arrays) at the National Institute of Standards and Technology in the US in proof-of-principle experiments. This work will support the eventual transition of the technique away from synchrotrons and into the laboratory and museum. An additional aim is to investigate the archaeometric capability of a prototype handheld XRD instrument, based on the same underlying technique but having much lower resolution. Previous work with this prototype device strongly suggests that the analysis of metallic heritage objects is an especially promising area. The avoidance of the need to extract samples from high-value and rare objects is a highly-significant advantage and is applicable in other research areas. These include palaeontology and the study of meteorites and planetary materials brought to Earth by sample-return missions.