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Three commercial TiO2 compounds (Degussa P25, Sachtleben UV100, and Millenium PC50) and their platinized forms have been studied by the time-resolved microwave conductivity (TRMC) method to follow their charge-carrier dynamics and to relate it to the photocatalytic activity for phenol degradation in TiO2 aqueous suspensions. The degradation reaction has been studied in detail, following the time evolution of the concentration of phenol and its intermediates by liquid chromatography. The results show that platinization has a distinct influence on the commercial compounds, decreasing globally the activity of P25 and increasing the activity of PC50 and UV100. An influence of charge-carrier lifetimes on the photoactivity of pure and platinized TiO2 samples has been evidenced.

Raman microscopy, with its unique versatility and special advantages of no sample preparation and nondestructive analysis of both inorganic and organic materials, is now well established as the best technique for studying pigments and their fillers in ancient or recent paintings. Here this technique was applied for the first time to prehistoric rock art. Microsampling was carried out on red and black parts of Palaeolithic paintings in the three caves Les Fieux, Les Merveilles and Pergouset in limestone of the Quercy District, Lot Department, France. The initial results are: (a) the identification of 'normal' haematite pigment in red microsamples from each cave; (b) the discovery of an additional, but rare, orange-red phase (A) which seems to be a disordered form of goethite; (c) the confirmation of amorphous carbon in some black microsamples; and (d) the recognition of Mn oxide/hydroxide in some other black microsamples. Hence Raman microscopy is sufficiently powerful for distinguishing different red and different black pigments without the use of additional complementary techniques. Hence it is now reasonable to envisage analysis with optical fibres and a remote sensor inside the caves in order to avoid damaging prehistoric rock art by microsampling.

This study aims to provide a better understanding of the Raman spectra of cobalt-based pigments in works of art. Systematic analyses of 21 industrial blue cobalt-based pigments were carried out by using elemental energy dispersive spectroscopy and phase analyses by X-ray diffraction (XRD) and Raman microspectroscopy, which led to the identification of 17 spinel Co-based pigments. All the minerals contained in each pigment were characterised by all three techniques and subsequently attributed to diluents, extenders, mineralisers or unreacted reagents or to the main mineral phase, whether it was pure or contained doping or lattice modifier elements. In the particular case where doping elements were in low concentration in the host mineral lattice, their distinction by XRD from non-doped spinel was impossible. On the contrary, Raman microspectroscopy turned out to be a perfect tool for detecting the presence of the doping agents in the spinel lattice. The determination of the elemental and mineralogical composition of the industrial blue cobalt-based pigments commercially available for artists and studied in this survey represents a significant increase in the amount of analytical data available for this type of pigment as well as a valuable addition in the characterisation by Raman microspectroscopy of these compounds in situ, on works of art.

Cellulose acetate, developed about 100 years ago as a versatile, semisynthetic plastic material, is used in a variety of applications and is perhaps best known as the basis of photographic film stock. Objects made wholly or partly from cellulose acetate are an important part of modern and contemporary cultural heritage, particularly in museum collections. Given the potential instability of the material, however, it is imperative to understand the aging mechanisms and deterioration pathways of cellulose ester plastics to mitigate decomposition and formulate guidelines for storage, exhibition, and conservation. One important aspect of this process is the ability to fully characterize the plastic, because variations in composition affect its aging properties and ultimate stability. In this Account, we assess the potential of a range of analytical techniques for plastics made from cellulose acetate, cellulose propionate, and cellulose butyrate. Comprehensive characterization of cellulose ester plastics is best achieved by applying several complementary analytical techniques. Fourier-transform IR (FTIR) and Raman spectroscopy provide rapid means for basic characterization of plastic objects, which can be useful for quick, noninvasive screening of museum collections with portable instruments. Pyrolysis GC/MS is capable of differentiating the main types of cellulose ester polymers but also permits a richly detailed compositional analysis of additives. Thermal analysis techniques provide a wealth of compositional information and thermal behavior. Thermogravimetry (TG) allows for quantitative analysis of thermally stable volatile additives, and weight-difference curves offer a novel means for assessing oxidative stability. The mechanical response to temperature, such as the glass transition, can be measured with dynamic mechanical analysis (DMA), but results from other thermal analysis techniques such as TG, differential scanning calorimetry (DSC), and dynamic load thermomechanical analysis (DLTMA) are often required to more accurately interpret the results. The analytical results from this study form the basis for in-depth studies of works of art fabricated from cellulose acetate. These objects, which are particularly at risk when stored in tightly sealed containers (as is often the case with photographic film), warrant particular attention for conservation given their susceptibility toward sudden onset of deterioration.

The identification of organic colorants in works of art (such as dyes on textiles or organic pigments) by Raman spectroscopy is generally limited by the presence of a strong fluorescence background. In this paper, the effectiveness of minimizing fluorescence in the analysis of Cape Jasmine (Gardenia augusta L.) by dispersive Raman spectroscopy at three different excitation wavelengths (633, 785 and 1064 nm) and by surface-enhanced Raman spectroscopy (SERS) with and without acid hydrolysis is evaluated and compared. It is shown that these vibrational techniques offer an alternative analytical approach, when, as is particularly the case of Cape Jasmine, sample preparation procedures that are routinely applied for natural organic dyes and pigments cause alterations that lead to low sensitivity in the more classical high-performance liquid chromatographyphotodiode array (HPLC-PDA) analytical protocols. Samples of the yellow dye G. augusta L. in the following forms were analyzed: dyed on alum mordanted wool, dyed on nonmordanted and alum mordanted silk, pigment precipitated on hydrated aluminum oxide, extract mixed with a protein binder and painted on glass, and as a water-based glaze applied on a mock-up of a typical Chinese wall-painting. Raman bands at 1537, 1209 and 1165 cm −1 are identified as discriminating markers for the carotenoid colorant components crocetin and crocin.

Spatially resolved element distributions generated by in situ X-ray fluorescence (XRF) line and area scans are shown to provide information about works of art which may not be obtainable from single spot spectra. In addition to generating visually powerful element maps and line profiles, this method also generates a spectrum at each image point, and this large data set is available for additional analysis. When generating line and area scans in the study of works of art, the collection parameters -including X-ray tube choice, spot size, step size, and scan time -must be optimized not only to produce the best signal, but also to perform the analysis within constraints imposed to ensure the security or safety of the object. Examples of the application of this method to several classes of works of art are presented, including illuminated manuscripts, paintings, bronze sculpture, and glazed ceramics.

The influence of niobium on the physicochemical properties of the Mo-V-O system and on its catalytic properties in the oxidation of ethane to ethylene and acetic acid is examined. Solids based on