The photostability of red synthetic organic pigments of three different chemical classes such as naphthol AS (PR112), diketopyrrolopyrrole (PR254 and 255), and quinacridone (PR122 and red shaded ...PV19) is investigated in the present work. In particular, the study focuses on pigments in powder form and in alkyd and acrylic paints which are widely used in art. The aim is to consider the influence of the pigments on the long-term stability of the paints when exposed to conditions of outdoor solar radiation. For this purpose, pigment powders as well as self-made and commercial paints were characterized by spectroscopic techniques before and after exposure to accelerated artificial solar radiation. Chemical and color changes were studied by micro-Raman, infrared, and UV–Vis spectroscopies. The pigment powders resulted to be stable to the ageing conditions applied. The photostability of the paints was evaluated by semi-quantitative interpretation of the infrared data, and it was found that the light ageing is indeed affecting the alkyd and acrylic binders, rather than the pigments. Additionally, in both, alkyd and acrylic aged paints a relative enrichment of pigments was registered on the surface, due to the photodegradation of the binders, which led to the formation of low-molecular-weight and volatile compounds. Finally, Hierarchical Cluster Analyses (HCA) of UV–Vis data proved that UV–Vis spectral features could be successfully used for the identification of the pigments in the paints, despite the light ageing.
•The characterizability and photostability of naphthol AS, diketopyrrolopyrrolo, and quinacridone pigments are investigated•Identification of the pigments in powder form, in acrylic and alkyd paints is achieved before and after exposure to simulated solar radiation•The study is carried out using non-invasive and non-destructive methods, combined with hierarchical clustering•The influence of the pigments on the photodegradation of the paints is studied
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Depth profiling with confocal micro-X-ray fluorescence spectroscopy (confocal micro-XRF) is a nondestructive analytical method for obtaining elemental depth profiles in the micrometer region. Up ...until now, the quantitative reconstruction of thicknesses and elemental concentration of stratified samples has been only possible with monochromatic, thus, synchrotron radiation. In this work, we present a new calibration and reconstruction procedure, which renders quantification in the laboratory feasible. The proposed model uses the approximation of an effective spot size of the optic in the excitation channel and relies on the calibration of the transmission of this lens beforehand. Calibration issues are discussed and validation measurements on thick multielement reference material and a stratified system are presented.
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IJS, KILJ, NUK, PNG, UL, UM
Megaelectronvolt-Secondary Ion Mass Spectrometry (MeV-SIMS) is an emerging ion beam analysis technique for molecular speciation and submicrometer imaging. Following the construction of different ...experimental setups a systematic investigation on the dependence of secondary ion yields on experimental parameters is crucial. Without this knowledge, results are hard to interpret as surface roughness, scan size and the position on the sample can influence the secondary ion count and misleading images can be obtained. Additionally, to achieve better reproducibility the optimal experimental conditions need to be well known. In this work, we present the results of investigations into the influence of the main experimental parameters on the secondary ion yield.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Secondary Ion Mass Spectrometry using MeV ion excitation was applied to analyse modern paint materials containing synthetic organic pigments and binders. It was demonstrated that synthetic organic ...pigments and binder components with molecular masses in the m/z range from 1 to 1200 could be identified in different paint samples with a high efficiency and in a single measurement. Different ways of mounting of mostly insulating paint samples were tested prior to the analysis in order to achieve the highest possible yield of pigment main molecular ions. As Time-of-Flight mass spectrometer for MeV Secondary Ion Mass Spectrometry is attached to the heavy ion microprobe, molecular imaging on cross-sections of small paint fragments was performed using focused ions. Due to the fact that molecules are extracted from the uppermost layer of the sample and to avoid surface contamination, the paint samples were not embedded in the resin as is usually done when imaging of paint samples using different techniques in the field of cultural heritage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Megaelectronvolt-Secondary Ion Mass Spectrometry (MeV-SIMS) is an emerging Ion Beam Analysis technique for molecular speciation and submicron imaging. Various setups have been constructed in the ...recent years. Still a systematic investigation on the dependence of MeV-SIMS yields on different ion beam parameters is missing. A reliable measurement method of the beam current down to the attoampere range is needed for this investigation. Therefore, a new detector has been added to the MeV-SIMS setup at the Ruđer Bošković Institute (RBI), which measures the current directly using a Si PIN-diode. In this work, we present the constructed system, its characteristics, and results of the first yield measurements. These measurements have already identified important factors that have to be considered while constructing a MeV SIMS setup.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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