The traditional labelling of archive documents (e.g., hand stamping) entails several limitations. It could affect the aesthetic value of the archive document and is easy to find and remove in case of the theft of the document. The use of a label that would not be easily visible by the naked eye would resolve both of these problems. One possibility in designing such label is the use of the elements that have a good response in X‐ray fluorescence (XRF) spectrum, are not disturbing in colour, and are not usually present in the archive materials themselves. This study focuses on such type of labelling, specifically, the tags based on the oxides of lanthanum, dysprosium, samarium, gadolinium, and niobium. For the material to be taken into account by the community, it has to fulfil several important characteristics, such as harmlessness to the archival documents, non‐toxicity, or long‐term stability. In the study, the long‐term stability of these tags was studied on model samples of lignocellulose materials subjected to several types of artificial ageing. The colour changes and changes in the intensity of the responses of the individual elements in the XRF spectra were evaluated. To simulate the practical use, the tags of minimal visibility to the naked eye were printed on samples of real archive materials, and their potential for detection using a handheld XRF spectrometer was studied. Both of the research parts should help bring this type of labelling closer to the field application.

中文翻译：

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隐形X射线荧光识别标签的长期稳定性

存档文件的传统标签（例如，手工压印）受到一些限制。它可能会影响存档文档的美学价值，并且在文档被盗的情况下很容易找到和删除。使用肉眼不易看到的标签可以解决这两个问题。设计此类标签的一种可能性是，使用在X射线荧光（XRF）光谱中具有良好响应，不干扰颜色且通常不在存档材料本身中的元素。这项研究集中在这种类型的标签上，特别是基于镧，、,、 mar，ni和铌的氧化物的标签。为了使社区能够考虑到这些材料，它必须具备几个重要的特征，例如对归档文件无害，无毒或长期稳定。在这项研究中，这些标签的长期稳定性是在经过多种人工老化的木质纤维素材料模型样品上进行的。评估了颜色变化和XRF光谱中各个元素响应强度的变化。为了模拟实际使用，将肉眼可见度最小的标签印在实际存档材料的样本上，并研究了使用手持式XRF光谱仪检测其潜力。这两个研究部分都应有助于使这种标签更接近现场应用。这些标签的长期稳定性是在经过多种人工老化的木质纤维素材料模型样品上进行研究的。评估了颜色变化和XRF光谱中各个元素响应强度的变化。为了模拟实际使用，将肉眼可见度最小的标签印在实际存档材料的样本上，并研究了使用手持式XRF光谱仪检测其潜力。这两个研究部分都应有助于使这种标签更接近现场应用。这些标签的长期稳定性是在经过多种人工老化的木质纤维素材料模型样品上进行研究的。评估了颜色变化和XRF光谱中各个元素响应强度的变化。为了模拟实际使用，将肉眼可见度最小的标签印在实际存档材料的样本上，并研究了使用手持式XRF光谱仪检测其潜力。这两个研究部分都应有助于使这种标签更接近现场应用。将肉眼可见度最小的标签印在实际的存档材料样本上，并研究了使用手持式XRF光谱仪进行检测的潜力。这两个研究部分都应有助于使这种标签更接近现场应用。将肉眼可见度最小的标签印在实际的存档材料样本上，并研究了使用手持式XRF光谱仪进行检测的潜力。这两个研究部分都应有助于使这种标签更接近现场应用。