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The Infrared Thermography (IRT) technique has been widely developed during the last years. IRT is useful to observe changes in the fields of physics and chemistry, and has turned out to be an important and indispensable non-destructive technique used for investigation of civil engineering works, with special attention to cultural heritage. In this research IRT has been used to study the crystallization of NaCl solution droplets with different initial concentrations (3.5, 14 and 26% weight). The crystallization was induced by evaporation of the solvent (water). Tests were carried out at two temperatures (25 and 50°C). We explained how the crystallization process is observed with IRT. The variations in emissivity recorded by the IRT described distinctly the different stages of salt crystallization. IRT allowed observing three phases. In phase I the mass diffusion within the droplet and differences in concentration and volume of the solution around the crystal germs nuclei were observed. Phase II is related to the final crystallization step, with the crystal growth and the complete evaporation of the solution. Phase III describes creeping associated with efflorescence formation. This phenomenon takes place as an intermittent decrease in the IR thermosignal which can be repeated up to 100 times in a 10 minutes interval. Different morphologies corresponded to different IRT phases. Thus, if only phases I-II are present, crystals have cubic shape or efflorescence-like with fan-shape. If phase III occurs, efflorescence-like crystals with spherulite shape develop. These spherulites can crystallize on the substrate or on previous crystals, growing by top-supplied creeping and showing an intermittent decrease of thermosignal. The study and comprehension of salt droplets crystallization by IRT is the first step in our research. Currently, we are testing different salt types and the response of salt crystallization in porous stones. Keywords: Infrared Thermography, emissivity, creeping, NaCl, temperature

In order to assess the durability of potential restoration sandstones for the cathedral ofStrasbourg (France), a comparative study was carried out on Triassic siliceous materials, socalled Meules and Vosgien sandstones. During relative humidity variations, dilations wereperformed before and after salt contamination using two salts, sodium chloride and sodiumsulfate, as well as two degrees of contamination on quarry and exposed sandstones. Sandstonebehaviors were reversible whatever the salt type: swelling under high relative humidityconditions and shrinking during low relative humidity stages. Sodium sulfate promoted onlyslight variations of dilation whilst deformation behaviors were greatly influenced by sodiumchloride that emphasized the contribution of deliquescence/recrystallization effect. As soon asthe salt had been dissolved, a slope variation related to constant swelling during high relativehumidity periods highlighted clay-salt interaction due to osmotic swelling. Thus, the dilationmethod allows determination of salt involvement on dilation behaviors during relative humiditycycles and the discrimination of sandstones.

Several new applications of cathodoluminescence (CL) have been developed during the last few years, including: combined CL imaging and/or spectroscopy and CL observations of carbonates previously considered to be non-luminescent or of minor interest. Basically, two previously unstudied types of carbonates were investigated: marbles, and recent shells. From numerous classical white marble samples, cathodomicrofacies were defined and described. A single cathodomicrofacies is generally characteristic of a given area. This finding permits identification of the source of white marbles and has been successfully applied to ancient marbles from different collections. Despite the well established idea that CL in biogenic carbonates is due solely to diagenetic phenomena, most recent biogenic carbonates show growth zonations which are enhanced under CL. This phenomenon is independent of shell mineralogy (calcite or aragonite), habitat (marine or fresh water), life mode or environment. Thus, the idea that unaltered shells are non-luminescent is contradicted. These observations have important implications for future studies of geochemical paleo-oceanic reconstructions as well as ontogenetic researches. Low-luminescing calcites are good examples of blue CL emission in natural calcite. Preliminary results are shown. One of the major advantages of using CL is that the original structure and texture of the sample is observable and there is no averaging of chemical information. CL gives in situ information on intrinsic (host lattice) luminescence emissions and the pattern of trace elements in the crystals. To quantitatively interpret the CL image, a non-destructive in situ method of chemical analysis is needed. Further progress in CL is likely to include quantitative spectroscopy and in situ chemical analyses.

When an ion beam in the energy range of a few MeV/amu impacts on a mineral, visible light can often be observed. This light, induced by energetic ions, is termed ionoluminescence (IL). The intensity and wavelength of the ionoluminescent light provide information concerning the nature of luminescence centers, such as trace substituents and structural defects, found in the mineral. This makes IL a useful complement to other methods of ion beam analysis (IBA), such as particle induced X-ray emission (PIXE) and Rutherford backscattering (RBS), in characterizing geological samples. In the present study, a proton or alpha particle beam was used for the IL excitation and IBA with a nuclear microprobe. The results obtained with IL were compared with those of cathodoluminescence (CL) and photoluminescence (PL).