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):6436-6444. doi: 10.1021/acs.analchem.8b00240. Epub 2018 Apr 17.
In the past decade macroscopic X-ray fluorescence imaging (MA-XRF) has become established as a method for the noninvasive investigation of flat painted surfaces, yielding large scale elemental maps. MA-XRF is limited by a lack of specificity, only allowing for indirect pigment identification based on the simultaneous presence of chemical elements. The high specificity of X-ray powder diffraction (XRPD) mapping is already being exploited at synchrotron facilities for investigations at the (sub)microscopic scale, but the technique has not yet been employed using lab sources. In this paper we present the development of a novel MA-XRPD/XRF instrument based on a laboratory X-ray source. Several combinations of X-ray sources and area detectors are evaluated in terms of their spatial and angular resolution and their sensitivity. The highly specific imaging capability of the combined MA-XRPD/XRF instrument is demonstrated on a 15th/16th century illuminated manuscript directly revealing the distribution of a large number of inorganic pigments, including the uncommon yellow pigment massicot ( o-PbO). The case study illustrates the wealth of new mapping information that can be obtained in a noninvasive manner using the laboratory MA-XRPD/XRF instrument.
在过去的十年中，宏观 X 射线荧光成像（MA-XRF）已成为一种用于非侵入式研究平面绘画表面的方法，可生成大规模元素图谱。MA-XRF 的局限性在于缺乏特异性，只能根据化学元素的同时存在来进行间接的颜料识别。X 射线粉末衍射（XRPD）图谱的高特异性已经在同步辐射设施中被用于（亚）微观尺度的研究，但该技术尚未在实验室光源中使用。本文介绍了一种基于实验室 X 射线源的新型 MA-XRPD/XRF 仪器的开发。根据空间和角度分辨率以及灵敏度，评估了几种 X 射线源和面探测器的组合。通过对一个 15 世纪/16 世纪的有照明手稿的直接研究，展示了组合式 MA-XRPD/XRF 仪器的高度特异性成像能力，直接揭示了大量无机颜料的分布情况，包括不常见的黄色颜料密陀僧（o-PbO）。该案例研究说明了使用实验室 MA-XRPD/XRF 仪器可以以非侵入式方式获得的大量新映射信息。
