Evaluation of Portable Raman for the Characterization of Salt Efflorescences at Petra, Jordan

Abstract

The advantages of using portable Raman spectrometer equipment, such as avoiding sampling and providing a higher number of results, are contrasted with some of its shortfalls that make other analytical techniques necessary to characterize salt efflorescences on historic buildings. In-situ analyses of salt efflorescences were carried out with a portable Raman at both the so-called ‘‘Silk Tomb’’ and ‘‘Monastery’’ rock-cut façades at the Archaeological Park of Petra (Jordan). Samples were also taken to be analyzed in the laboratory with X-ray diffraction (XRD) and Environmental Scanning Electron Microscope with Energy-Dispersive X-ray spectroscopy and Cathodoluminescence (ESEM-EDS-CL). This research shows the pros and cons of these analytical techniques—and how they complement each other—to identify the occurrence and determine the origin of soluble salts, which are deeply damaging these rock-cut monuments by salt crystallization processes.