Evaluation of portable Raman for the characterization of salt efflorescences at Petra, Jordan

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 fa̧ades 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.