AXES Research Group, Department of Chemistry , University of Antwerp , Groenenborgerlaan 171 , B-2020 Antwerp , Belgium.
Department of Materials Science , Delft University of Technology , Mekelweg 2 , 2628 CD Delft , The Netherlands.
Anal Chem. 2018 Jun 5;90(11):6445-6452. doi: 10.1021/acs.analchem.8b00241. Epub 2018 Apr 17.
At or below the surface of painted works of art, valuable information is present that provides insights into an object's past, such as the artist's technique and the creative process that was followed or its conservation history but also on its current state of preservation. Various noninvasive techniques have been developed over the past 2 decades that can probe this information either locally (via point analysis) or on a macroscopic scale (e.g., full-field imaging and raster scanning). Recently macroscopic X-ray powder diffraction (MA-XRPD) mapping using laboratory X-ray sources was developed. This method can visualize highly specific chemical distributions at the macroscale (dm). In this work we demonstrate the synergy between the quantitative aspects of powder diffraction and the noninvasive scanning capability of MA-XRPD highlighting the potential of the method to reveal new types of information. Quantitative data derived from a 15th/16th century illuminated sheet of parchment revealed three lead white pigments with different hydrocerussite-cerussite compositions in specific pictorial elements, while quantification analysis of impurities in the blue azurite pigment revealed two distinct azurite types: one rich in barite and one in quartz. Furthermore, on the same artifact, the depth-selective possibilities of the method that stem from an exploitation of the shift of the measured diffraction peaks with respect to reference data are highlighted. The influence of different experimental parameters on the depth-selective analysis results is briefly discussed. Promising stratigraphic information could be obtained, even though the analysis is hampered by not completely understood variations in the unit cell dimensions of the crystalline pigment phases.
在绘画艺术品的表面或以下，存在着有价值的信息，这些信息可以深入了解物体的过去，例如艺术家的技法和创作过程，以及其保存历史，同时还可以了解其当前的保存状况。在过去的 20 年中，已经开发出了各种非侵入性技术，可以通过局部（通过点分析）或宏观尺度（例如全场成像和光栅扫描）来探测这些信息。最近，使用实验室 X 射线源开发了宏观 X 射线粉末衍射（MA-XRPD）测绘技术。该方法可以在宏观尺度（dm）上可视化高度特定的化学分布。在这项工作中，我们展示了粉末衍射的定量方面与 MA-XRPD 的非侵入式扫描能力之间的协同作用，突出了该方法揭示新类型信息的潜力。从 15 世纪/16 世纪的一幅有照明的羊皮纸上获得的定量数据揭示了三种不同水羟铅矿-方铅矿组成的铅白颜料，而对蓝色蓝铜矿颜料中的杂质进行定量分析则揭示了两种不同类型的蓝铜矿：一种富含重晶石，另一种富含石英。此外，在同一文物上，突出了该方法由于利用测量的衍射峰相对于参考数据的偏移而具有的深度选择性。简要讨论了不同实验参数对深度选择性分析结果的影响。即使由于对晶体颜料相的晶胞尺寸的不完全理解而导致分析受到阻碍，仍可以获得有前途的地层信息。
