Exploring street art paintings by microspatially offset Raman spectroscopy

Abstract

Microspatially offset Raman spectroscopy (micro-SORS) is a recently developed analytical technique combining SORS with microscopy. With this method, highly diffusely scattering microlayers such as painted stratigraphies can be noninvasively probed. In this study, we explore micro-SORS for identifying the chemical composition of subsurface layers in real, street art mural paintings as a new nondestructive method for the characterization of their stratigraphy. Two micro-SORS variants, defocusing and full micro-SORS, were tested and compared.

Spatially offset Raman spectroscopy

“…In this case, variation of spatial offset can lead to the crossing over from probing one heterogeneous domain to another, leading to lateral effects being potentially attributed to spectral variations at different depths and complicating SORS data analysis and interpretation. This can be mitigated by repeating the SORS measurements at multiple locations on the sample surface and averaging the acquired signals or sampling with lower spatial resolution instruments 148,149 .…”

An in-and-out-the-lab Raman spectroscopy study on street art murals from Reggio Emilia in Italy

“…Micro-Raman spectroscopy performed on selected cross-sections not only confirmed this but was also able to locate the rutile in the stratigraphy. We notice those recent developments in the use of the Raman spectroscopy, in particular of the SORS (Spatially Offset Raman Spectroscopy) technique, could allow to obtain stratigraphic information on paintings without the need for sampling [34].…”

Recent advances in linear and nonlinear Raman spectroscopy. Part XIII

“…Botteon et al used microspatially offset Raman spectroscopy (micro‐SORS) to explore street art paintings. Two micro‐SORS variants, defocusing and full micro‐SORS, were tested and compared . Culka and Jehlicka examined sequentially shifted excitation as a tool for suppression of laser‐induced fluorescence in mineralogical applications using portable Raman spectrometers.…”

“…Two micro-SORS variants, defocusing and full micro-SORS, were tested and compared. [197] Culka and Jehlicka examined sequentially shifted excitation as a tool for suppression of laser-induced fluorescence in mineralogical applications using portable Raman spectrometers. This novel approach of obtaining high quality Raman spectra of minerals containing trace amounts of fluorescenceinducing components (such as rare earth elements) with portable instrumentation opens up new possibilities for in situ spectroscopic analyses in the fields of mineralogy and geology.…”