Non-Destructive Identification On Relics'Pigments By Fiber Optics Reflectance Spectroscopy And Monitoring The Pigments' Changes In The Harmful Gases

Fiber optics reflectance spectroscopy (FORS) is a kind of analytical method, which can obtain the information of the material surface layer by the measurement to the light reflectance of the different wavelengths. It is used to identify the pigments on the colored relics and to monitor the changes of color in the harmful gases non-destructively.With our self-developed Fiber Optics Reflectance Spectrophotometer, the pigments on the color relics in Dazu Stone Sculpture Area in Chongqing municipality, in the tomb of King Lintong of the Ming Dynasty in Chang'an County and in Yang mausoleum of the Han Dynasty have been measured and their chromogenic components determined. The comparison between the results of FORS and those of X-ray diffraction analysis and X-ray fluorescence tells that FORS is both simple and reliable and a sort of new method to identify the pigments on the relics.Moreover, the changes of sixteen pure and mixed pigments in H2S, NO2 harmful gases and different humidity have been measured by FORS. By the comparison the peaks' changes in the reflectance and first derivative spectra of the different pigments, some regular principles of the pigments' changes have been concluded, the mechanism discussed and the scientific data provided for the establishment of the optimum environment to protect the relics effectively.