[Research Method and Spectral Analysis of Ancient Polychromatic Silicate Artifacts]

The spectral properties, chemical compositions and phases of materials constituting the surface of 5 ancient polychromatic silicate artifacts have been analyzed non-invasively with self-built multispectral imaging system, X-ray fluorescence spectrometer (XRF) and laser Raman spectrometer (LRS). Based on spectral response in multispectral images, materials constituting the surface of 5 samples can be divided into different areas, and most of blue, green, purple areas with fluorescence behavior are also mapped. The results of XRF indicate that the chemical compositions of areas are different, but the major compositions of them are SiO(2), PbO, BaO. 5 samples mainly belong to PbO-BaO silicates. The coloring agents of all areas with fluorescence behavior are Cu ions. A variety of mineral phases including vitreous phase, Chinese blue, Chinese purple, quartz, hematite, lead carbonate, amorphous carbon and so on, are also identified by LRS. Chinese blue and Chinese purple can emit infrared radiation when excited by visible LED. The result of LRS is verified by X-ray diffraction (XRD). Combining the multispectral imaging area-measurement technique used to research paintings, and XRF, LRS which are usually used to analyze chemical composition of silicate artifacts, the present research proposes a more efficient and non-invasive research method to analyze ancient polychromatic silicate artifacts. Spectral characteristic and chemical composition of the sample are connected when spectral images, X-ray fluorescence spectra and Laser Raman spectra are combined. It has great significance for increasing efficiency of analysis, enhancing the overall understanding of silicate artifacts and decreasing risk of damage.