Castellucci 2000 Case Study Sample

and Castellucci 2000). Examples are the introduction of lasers, Fourier transform (FT) Raman, charge-coupled device (CCD) detectors, confocal Raman spectroscopy and fiber-optics, that allowed conservation scientists to record molecular spectra of minute samples or directly from the art object.

Case study
Red pigment samples were collected from the early Christian necropolis of El-Bagawt at Kharga Oasis, Egypt. El-Bagawat necropolis is dating back to the 4th century AD. Two of the most outstanding and best preserved of the decorated chapels are named ‘Chapel of the Exodus’ and ‘Chapel of Peace’. Raman spectra were recorded in the near infra red excitation line (785 nm) using a Renishaw InVia Raman spectrometer. A Leica polarized microscope
The origins of the monastery are due to the 4th century AD. FTIR–ATR spectra were collected on a Perkin Elmer spectrometer 400 equipped with an ATR detector (attenuated total reflectance) in the wavelength range of 4000–650 cm–1, at a spectral resolution of 4 cm–1 over 32 scans. In attenuated total reflectance (ATR) spectroscopy, the sample is placed in contact with a special crystal which is composed of a material with a high index of refraction [e.g., zinc selenide (ZnSe), thallium bromide iodide (KRS-5), Ge]. Figure 6 shows FTIR–ATR spectrum extracted from the imaging of the green paint sample. Mineralogical species of green earths can be distinguished in the 3400–3700 cm−1 and 950–1100 cm−1 range. Glauconite was characterized by the broad peaks in the 1100–944 cm−1 region. (see Figure
1279- 1212 BC)- at El-Assasif district, El-Qurna necropolis (Luxor-Upper Egypt). The visible reflectance spectra of the samples were obtained by a Miniscan® XE Plus spectrophotometer (HunterLab). The reflectance spectra were registered in the visible wavelengths domain (from 400 to 700 nm). Chromatic values are expressed as color coordinates in the CIE L*a*b* color system (1976) under the standard illuminant D65 and a 10º/observer. The spectral resolution was 10 nm, the spectral bandwidth was < 12 nm and the wavelength accuracy was 1 nm. The light source was Xenon Flash and the viewed sample area was 25 mm (1.00 in). The reflectance spectra of the Egyptian blue pigment show a slope at the wavelength higher than 650 nm. The green pigments tend to give a sharp slope at wavelength higher than 630 nm and return to increase after this wavelength. The samples show different dominant wavelengths in the greenish-yellow zone meanly at 570 nm. Some chromatic changes of the blue pigment mainly in form of green colors are chromatically characterized by a small shift at 520 and 580 nm. The reflectance spectra of hematite show a sharp positive slope at wavelengths higher than 600 nm, while goethite show a slope lower than 600 nm. The reflectance spectra helped to identify and differentiate the different colors of the samples and in particular the red and yellow ocher, as well as between Egyptian