Characterizing the Intrinsic Fluorescence Properties of Historical Painting Materials: The Case Study of a Sixteenth-Century Mesoamerican Manuscript

Abstract

Ultraviolet visible (UV-Vis) fluorescence spectroscopy is widely used to study polychrome objects and can help to identify the nature of certain materials when they present specific fluorescent properties. However, given the complexity of the stratified and heterogeneous materials under study, the characterization of an intrinsic fluorescence related to a given constituent (a pigment or a binder composing a paint layer for example) is not straightforward, and the recorded raw data need to be corrected for a number of effects that can influence the detected spectral distribution. The application of standard correction procedures to experimental fluorescence data gathered on the polychromatic surface of the Codex Borbonicus, a 16th-century Aztec manuscript, is described. The results are confronted to an alternate new methodology that is based on the hypothesis of transparent non-scattering paint layers. This second approach allows to establish more clearly the material origin of the detected emission and to discriminate apparent fluorescence (emitted by the substrate and transmitted through the paint layers) from actual intrinsic emission generated by the coloring materials under study. The results show that most of the various emission profiles detected in the paint layers of the manuscript actually originate from a unique fluorophore (composing the substrate) and should not be used to characterize the coloring materials.

Short- and Long-Term Effects of X-ray Synchrotron Radiation on Cotton Paper

“…The spectroradiometer was placed perpendicular to the sample, and illumination was done with either a DH-2000 halogen source (Ocean Optics) for the reflectance measurements or a UV Prior lumen 200 source for the luminescence measurements, at a 45°angle as previously described. 36 The UV light was filtered with a bandpass filter (365FS25-25, V345-61) to obtain a narrow excitation range centered at 365 nm with full width at halfmaximum (FWHM) = 20 nm (source spectrum in Figure S2 in the Supporting Information). A long-pass filter (cutoff wavelength: 380 nm) was placed in front of the detector to remove diffuse reflection of the excitation by the material.…”

“…The noninvasive diffuse reflectance and luminescence of the paper were measured with a UV–vis–near-infrared (NIR) spectroradiometer (Specbos 1211UV, JETI). The spectroradiometer was placed perpendicular to the sample, and illumination was done with either a DH-2000 halogen source (Ocean Optics) for the reflectance measurements or a UV Prior lumen 200 source for the luminescence measurements, at a 45° angle as previously described . The UV light was filtered with a bandpass filter (365FS25-25, V345-61) to obtain a narrow excitation range centered at 365 nm with full width at half-maximum (FWHM) = 20 nm (source spectrum in Figure S2 in the Supporting Information).…”

Methodology for dyes purification by preparative bidimensional offline reversed‐phase high‐performance liquid chromatography separation based on mobile phase pH change: Case study of Justicia spicigera

“…The non-invasive characterization study of the coloring materials of the Codex Borbonicus, a 16th-century Aztec manuscript, was previously carried out to contribute to Article Related Abbreviations: 1 the understanding of its creation process [1][2][3][4]. Justicia spicigera Schltdl.…”

“…Justicia spicigera Schltdl. (Acanthaceae), an endemic plant from Central America was tentatively identified in paint layers by comparison of the in situ Raman and UV-visible (UV-Vis) fluorescence emission signals with data from the literature [2,5]. The unique record of the use of this dye in a manuscript, to the authors' knowledge, and the scarcity of information regarding the chemical composition of the colored extract motivated its analysis in the laboratory.…”