Raman Studies Of The Pigments In Ancient Wall Paintings And Dyes

Raman spectroscopy, as the "fingerprint" of materials, has become a popular technique for the analysis of cultural and conservation. Raman spectroscopy, as the "fingerprint" of materials, has become a popular technique for the analysis of cultural and conservation. It has emerged as an alternative technique of surface material analysis by playing the in situ detection, non-destructive and high sensitivity of features, particularly in the relics and precious works of art. Raman spectroscopy can determine the molecular symmetry, the internal forces and structural features such as rotational energy levels of vibration by analyzing the Raman frequency shift of molecular vibration, and thus analysis to identify the material. The applicability of portable fiber optic Raman spectroscopy is to make high-precision analysis for in situ samples of the artifacts by its outstanding flexibility. Because of the particular frangibility of some valuable relics and artifacts, it is very important to ensure to follow the security , integrity principle for using any means of analyzing . The portable Raman spectroscopy meet the right contacts and easy to move for the testing of those possible damage to the cultural needs with its in situ, non-destructive, non-invasive detection method. Currently, the research interest of the world cultural heritage protection and rehabilitation is rising. This is precisely because of the breakthrough to the detection technical limitations in the past. China is the only country have the continuous history and enduring powers of civilization, whose history and artistic value of heritage is world famous. Use scientific methods to analyze and promote the historical heritage of our country is the most direct communication with the civilization and cultural development around the world. And this is the way that most can be understand by the researchers. Meanwhile, in the face of the particularity and independence of the cultural object, to improve portable Raman spectroscopy platform for the archaeological site, set up the standardized operational processes of in situ Raman analysis for on-site inspection, is very important for advancing the Raman spectroscopy into a heritage standardization of detection methods to protect. In this research and cultural background, this thesis includes the following elements of innovative design and completed studis:1. The establishment of laboratory simulation of a portable fiber optic Raman detection system. Simulated in the laboratory environment to ensure the security of Raman spectroscopy detection for pigment samples, to improve the applicability and the sensitivity of portable Raman spectroscopy detection. On the basis of simulation set up a platform for the application of in situ portable Raman spectroscopy detection in the archaeological sites. Plans to establish a database of the minerals (source-dependent) and effective pigments in samples as a reference system for archaeological analysis.2. Attempt to frame a operating process for the portable fiber Raman spectroscopy detection of mineral pigments in artifacts. To ensure sample security as the prerequisite for minerals and mineral pigments, test set operable standard operating procedures for pigments in color artifacts. Improve the detection process of portable fiber Raman used in archaeological excavation site with the high security, high applicability and high sensitivity. For the first time to test the establishment of the murals of Dunhuang Grottoes heritage-site detection method and operation procedures, and plans to establish a database for later analysis of the corresponding protection to provide scientific data as reference.3. Anylusis a piece of fragment of Mogao Grottoes in Dunhuang with portable fiber Raman spectroscopy. Identify the material of mineral pigments on the fragment compared with Raman spectra information of mineral samples and associated vibrational exclusion of mineral impurities and other information from reference. For the fresco fragments on different areas with different colors as red paint, as covering other pigments or dyes to produce color difference in the blue area, and the components of complex pigments mix in orange area and other distinguish components may be identified.4. The normal Raman and surface enhanced Raman scattering (SERS) spectra of flavanthrone and indanthrone are obtained at several excitation wavelengths. The reason of chosing these two molecules is they may have environmental degradation and prone to mutual conversion. The spectral assignments are aided by density functional calculations. Since both molecules have very high symmetry (C2h) including a center of inversion, we expect that the modes of u symmetry will be forbidden in the normal Raman spectrum.