Home About us Contact
|
Home About us Contact | ||
|
|
||
micro-Raman Spectroscopy (micro-raman + spectroscopy)
Selected AbstractsFactors affecting the formation of misoriented domains in 6H-SiC single crystals grown by PVT methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2009T. H. Peng Abstract Misoriented domains (MDs) are common defects in 6H-SiC single crystals. We performed an experimental study on the formation of MDs in 2-inch 6H-SiC single crystals. Micro-Raman spectroscopy revealed that the polytype of MDs was mainly 4H-SiC. By changing growth conditions, it was found that the MDs' formation was closely related to growth rate and the position of highest temperature relative to growth interface. When the growth rate of ingots was relatively high the MDs were more likely to form. Furthermore, the nearer growth interface the position of highest temperature was, the larger the size of the MDs. Based on our experimental findings we suggested that the MDs' formation and the polytype switching from 6H- to 4H-SiC were due to too large axial and/or radial temperature gradients. The results would be helpful to improve the quality of SiC single crystals grown by PVT technique. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of Electric Field on Microstructures of Pentacene Thin-Films in Field-Effect Transistors,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2008L. Cheng Abstract We report on electric-field-induced irreversible structural modifications in pentacene thin films after long-term operation of organic field-effect transistor (OFET) devices. Micro-Raman spectroscopy allows for the analysis of the microstructural modifications of pentacene in the small active channel of OFET during device operation. The results suggest that the herringbone packing of pentacene molecules in a solid film is affected by an external electric field, particularly the source-to-drain field that parallels the a,b lattice plane. The analysis of vibrational frequency and Davydov splitting in the Raman spectra reveals a singular behavior suggesting a reduced separation distance between pentacene molecules after long-term operations and, thus, large intermolecular interactions. These results provide evidence for improved OFET performance after long-term operation, related to the microstructures of organic semiconductors. It is known that the application of large electric fields alters the semiconductor properties of the material owing to the generation of defects and the trapping of charges. However, we first suggest that large electric fields may alter the molecular geometry and further induce structural phase transitions in the pentacene films. These results provide a basis for understanding the improved electronic properties in test devices after long-term operations, including enhanced field-effect mobility, improved on/off current ratio, sharp sub-threshold swing, and a slower decay rate in the output drain current. In addition, the effects of source-to-drain electric field, gate electric field, current and charge carriers, and thermal annealing on the pentacene films during OFET operations are discussed. [source] Micro-Raman spectroscopy of decorated pottery from the Iberian archaeological site of Puente Tablas (Jaén, Spain, 7th,4th century B.C.)JOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2010D. Parras Abstract In this paper, Raman spectroscopy is used for the first time to identify the pigments on decorated antique Iberian pottery. Ceramic fragments of type Real and others from the archaeological excavation in the oppidum Puente Tablas were examined. Different types of iron oxide pigments (hematite and goethite) were identified, along with amorphous carbon. In some samples, the presence of chalk or gypsum could be demonstrated. Some unattributed Raman bands are believed to be associated either with post-burial organic deposition or with silicate materials that are present in red ochre. It was possible to relate the findings with geological data from the region and to make assumptions on a local production. Copyright © 2009 John Wiley & Sons, Ltd. [source] In vivo study on the protection of indole-3-carbinol (I3C) against the mouse acute alcoholic liver injury by micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2009Aiguo Shen Abstract Micro-Raman spectroscopy (MRS) was utilized for the first time to evaluate the effect of indole-3-carbinol (I3C) on acute alcoholic liver injury in vivo. In situ Raman analysis of tissue sections provided distinct spectra that can be used to distinguish alcoholic liver injury as well as ethanol-induced liver fibrosis from the normal state. Sixteen mice with liver diseases including acute liver injury and chronic liver fibrosis, and eight mice with normal liver tissues, and eight remedial mice were studied employing the Raman spectroscopic technique in conjunction with biomedical assays. The biochemical changes in mouse liver tissue when liver injury/fibrosis occurs such as the loss of reduced glutathione (GSH), and the increase of collagen (,-helix protein) were observed by MRS. The intensity ratio of two Raman peaks (I1450/I666) and in combination with statistical analysis of the entire Raman spectrum was found capable of classifying liver tissues with different pathological features. Raman spectroscopy therefore is an important candidate for a nondestructive in vivo screening of the effect of drug treatment on liver disease, which potentially decreases the time-consuming clinical trials. Copyright © 2008 John Wiley & Sons, Ltd. [source] Raman microscopic investigation of paint samples from the Rosalila building, Copan, HondurasJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2006Rosemary A. Goodall Abstract Micro-Raman spectroscopy was applied to the study of multiple layered wall paints from the Rosalila temple, Copan, Honduras, which dates to the Middle Classic period (A.D. 520 to 655). Samples of red, green and grey paint and a thick white overcoating were analysed. The paint pigments have been identified as hematite, celadonite or green earth and a combined carbon/mica mixture. By combining Raman spectroscopy with micro-ATR infrared spectroscopy and environmental scanning electron microscopy (ESEM), a detailed study has been made of the materials and processes used to make the stucco and paints. The use of green earth as a green pigment on Maya buildings has not been reported before. The combination of carbon and muscovite mica to create a reflective paint is also a novel finding. Copyright © 2006 John Wiley & Sons, Ltd. [source] Bronze Age painted plaster in Mycenaean Greece: a pilot study on the testing and application of micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8-9 2004Ann Brysbaert Abstract Since the first discoveries of Minoan and Mycenaean painted plaster around the end of the 19th and early 20th centuries, iconographic and, to a lesser extent, technological studies have gone hand in hand in order to understand how these prehistoric societies were able to produce some of the earliest and most significant works of art in Bronze Age Europe and the eastern Mediterranean. These paintings claim to be among the first to be executed in the buon fresco technique. Past technological studies employed wet chemical methods, x-ray diffraction (XRD), optical emission spectroscopy and a range of microscopic techniques based on cross-sections of samples in order to investigate these fragmentary paintings. Most of these methods required destructive sampling and this is now, rightly so, very much restricted. Consequently, other non-micro-destructive approaches are being tested at present. Micro-Raman spectroscopy (MRS) has proven more than once its potential for non-destructive analysis of works of art and in archaeology in the recent past. Its application to this early fragmentary material is presented here for the first time. Interesting results were the identification of both organic (indigo) and non-crystalline materials (limonite), which complements the knowledge obtained from traditionally used techniques. Although not without problems (high fluorescence prevented identification of Egyptian Blue), non-destructive MRS yielded results comparable to XRD and provided the first identification of indigo blue on this medium, and can hence be considered very useful in future sample-reducing strategies considering these scarce materials. Copyright © 2004 John Wiley & Sons, Ltd. [source] Pigments and binders in the wall paintings of Santa Maria della Steccata in Parma (Italy): the ultimate technique of ParmigianinoJOURNAL OF RAMAN SPECTROSCOPY, Issue 8-9 2004Danilo Bersani Abstract Micro-Raman spectroscopy and gas chromatography combined with mass spectrometry (GC,MS) were employed to investigate the materials used in the wall paintings by the older Parmigianino (Francesco Mazzola, 1503,1540) on the arch over the main altar in the church of Santa Maria della Steccata in Parma, Italy. The pigments used by the artist and those added by later restorations are characterized by micro-Raman spectroscopy. GC,MS identified the organic binding media in the paint samples and revealed the presence of polysaccharides in the plaster. These investigations may be useful for a comparison with the technique of the young Parmigianino, author of wall paintings in the church of S. Giovanni Evangelista in Parma in the 1520s. Copyright © 2004 John Wiley & Sons, Ltd. [source] MICRO-RAMAN SPECTROSCOPY CHARACTERIZATION OF DELLA ROBBIA GLAZES,ARCHAEOMETRY, Issue 4 2007M. SENDOVA Micro-Raman spectroscopy and the laser-induced transformation technique were used for systematic study of five coloured glazes on Saint John the Baptist (29 inch tondo), a majolica terracotta relief attributed to Luca Della Robbia and on permanent exhibit in The John and Mable Ringling Museum of Art. We suggest that ions in a lead silicate matrix, called ,lead ultramarine', could contribute to the famous Della Robbia blue colour, in addition to the effect of Co atoms as suggested previously by Pappalardo et al. (2004). The original yellow glaze contains lead(II) antimonate. The green is a mixture of the yellow and blue pigments, the brown contains hematite, and the white glaze contains tin dioxide as an opacifier. The use of lead oxide as a main fluxing agent is confirmed by laser-induced micro-crystallization. [source] Apatite-forming ability (bioactivity) of ProRoot MTAINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2010M. G. Gandolfi Gandolfi MG, Taddei P, Tinti A, Prati C. Apatite-forming ability (bioactivity) of ProRoot MTA. International Endodontic Journal, 43, 917,929, 2010. Abstract Aim, Apatite-forming ability, considered as an index of bioactivity (bond-to-bone ability), was tested on ProRoot MTA cement after immersion in phosphate-containing solution (DPBS). Methodology, Disk samples were prepared and immersed in DPBS for 10 min, 5 h, 1 and 7 days. The cement surface was studied by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, by micro-Raman spectroscopy and by environmental scanning electron microscope with energy dispersive X-ray (ESEM-EDX) analyses. The pH of the storage solution was also investigated. Results, Spectroscopic analyses revealed calcium phosphate bands after 5-h immersion in DPBS. After 1 day, an even coating composed of apatite spherulites (0.1,0.8 micron diameter) was observed by ESEM/EDX. After 7 days, its thickness had increased. Apatite nucleation had already occurred after 5-h immersion. At this time, the presence of portlandite (i.e. Ca(OH)2, calcium hydroxide) on the cement surface was also observed; at longer times, this component was released into the medium, which underwent a remarkable pH increase. Conclusions, The study confirms the ability of ProRoot MTA to form a superficial layer of apatite within hours. The excellent bioactivity of ProRoot MTA might provide a significant clinical advantage over the traditional cements used for root-end or root-perforation repair. [source] Direct analysis of clinical relevant single bacterial cells from cerebrospinal fluid during bacterial meningitis by means of micro-Raman spectroscopyJOURNAL OF BIOPHOTONICS, Issue 1-2 2009Michaela Harz Abstract Bacterial meningitis is a relevant public health concern. Despite the availability of modern treatment strategies it is still a life-threatening disease that causes significant morbidity and mortality. Therefore, an initial treatment approach plays an important role. For in-time identification of specific bacterial pathogens of the cerebrospinal fluid (CSF) and emerged antimicrobial and adjunctive treatment, microbiological examination is of major importance. This contribution spotlights the potential of micro-Raman spectroscopy as a biomedical assay for direct analysis of bacteria in cerebrospinal fluid of patients with bacterial meningitis. The influence of miscellaneous artificial environments on several bacterial species present during bacterial meningitis was studied by means of Raman spectroscopy. The application of chemometric data interpretation via hierarchical cluster analysis (HCA) allows for the differentiation of in vitro cultured bacterial cells and can also be achieved on a single cell level. Moreover as proof of principle the investigation of a CSF sample obtained from a patient with meningococcal meningitis showed that the cerebrospinal fluid matrix does not mask the Raman spectrum of a bacterial cell notably since via chemometric analysis with HCA an identification of N. meningitidis cells from patients with bacterial meningitis could be achieved. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ageing of calcium silicate cements for endodontic use in simulated body fluids: a micro-Raman studyJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2009Paola Taddei Abstract To evaluate bioactivity properties, a calcium silicate experimental cement (wTC) and a phosphate-doped wTC cement (wTC-TCP) were aged for different times (1,180 days) at 37 °C in two simulated body fluids, i.e. Dulbecco's phosphate buffered saline (DPBS) and Hank's balanced salt solution (HBSS). The cements were analyzed by micro-Raman spectroscopy to investigate the presence of calcium phosphate deposits and the composition changes as a function of the storage time (hydration of anhydrite/gypsum and formation of ettringite; hydration of belite/alite and formation of hydrated silicates). After 1 day of ageing in DPBS, the two cements already showed a different behavior: only the surface of wTC-TCP cement showed the band at 965 cm,1, suggesting the formation of a detectably thick calcium phosphate deposit. The trend of the I965/I990 Raman intensity ratio indicated the formation of a meanly thicker apatite deposit on the wTC-TCP cement until 90 days. After 60 days of ageing in DPBS, the thickness of the apatite deposit on wTC and wTC-TCP was about 200 and 500 µm, respectively, whereas at 180 days, the two cements did not appear significantly different (thickness of about 900 µm). The bioactivity of both cements in HBSS was less pronounced than in DPBS, according to the lower phosphate concentration of HBSS; at the same time, higher amounts of calcite were found on the surface of both cements. The wTC-TCP cement showed a higher bioactivity in this medium also; after 180 days, the thickness of the apatite deposit on wTC and wTC-TCP was < 50 µm and about 100 µm, respectively. Copyright © 2009 John Wiley & Sons, Ltd. [source] Use of micro-Raman spectroscopy to study reaction kinetics in blended white cement pastes containing metakaolinJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2009Moisés Frías Abstract Curing temperature is known to play an important role in the formation, development, and stability of the hydrated phases appearing during pozzolanic reactions (chemical reaction between puzzolanic addition, metakaolin (MK), and calcium hydroxide from cement hydration). A typical example of this important reaction is to be found in metakaolin-bearing cement pastes, characterized by hexagonal phases whose thermodynamic stability declines with rising temperature. These phases cannot be exhaustively researched with traditional techniques (such as X-ray diffraction) due to their poor crystallinity. Consequently, micro-Raman spectroscopy was used in the present study to explore the behavior of white cement paste blends containing 0, 10, and 25% MK at two curing temperatures (20 and 60 °C). This led to the identification, for the first time using Raman spectroscopy, of phases C2ASH81 (stratlingite) and C3ASH6, which appear in the MK,white cement reaction. The CSH gel formed was characterized by Q1 dimers and a C/S ratio of 1.3,1.5. Raising the curing temperature favored the formation of C4AH13. Copyright © 2009 John Wiley & Sons, Ltd. [source] In vivo study on the protection of indole-3-carbinol (I3C) against the mouse acute alcoholic liver injury by micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2009Aiguo Shen Abstract Micro-Raman spectroscopy (MRS) was utilized for the first time to evaluate the effect of indole-3-carbinol (I3C) on acute alcoholic liver injury in vivo. In situ Raman analysis of tissue sections provided distinct spectra that can be used to distinguish alcoholic liver injury as well as ethanol-induced liver fibrosis from the normal state. Sixteen mice with liver diseases including acute liver injury and chronic liver fibrosis, and eight mice with normal liver tissues, and eight remedial mice were studied employing the Raman spectroscopic technique in conjunction with biomedical assays. The biochemical changes in mouse liver tissue when liver injury/fibrosis occurs such as the loss of reduced glutathione (GSH), and the increase of collagen (,-helix protein) were observed by MRS. The intensity ratio of two Raman peaks (I1450/I666) and in combination with statistical analysis of the entire Raman spectrum was found capable of classifying liver tissues with different pathological features. Raman spectroscopy therefore is an important candidate for a nondestructive in vivo screening of the effect of drug treatment on liver disease, which potentially decreases the time-consuming clinical trials. Copyright © 2008 John Wiley & Sons, Ltd. [source] In situ chemical analysis of modern organic tattooing inks and pigments by micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2008Kelvin W. C. Poon Abstract The chemical composition of tattooing pigments has varied greatly over time according to available technologies and materials. Beginning with naturally derived plant and animal extracts, to coloured inorganic oxides and salts, through to the modern industrial organic pigments favoured in today's tattooing studios. The demand for tattooing is steadily growing as it gains cultural popularity and acceptance in today's society, but ironically, increasing numbers of individuals are seeking laser removal of their tattoos for a variety of reasons. Organic pigments are favoured for tattooing because of their high tinting strength, light fastness, enzymatic resistance, dispersion and relatively inexpensive production costs. Adverse reactions have been reported for some organic inks, as well as potential complications, during laser removal procedures stemming from the unintentional creation of toxic by-products. Currently, regulatory bodies such as the US Food and Drug Administration have not approved any coloured inks to be injected into the skin, and tattoo ink manufacturers often do not disclose the ingredients in their products to maintain proprietary knowledge of their creations. A methodology was established using micro-Raman spectroscopy on an animal model to correctly identify the constituents of a selection of modern, organic tattoo inks in situ or post procedure, within the skin. This may serve as a preliminary tool prior to engaging in Q-switched laser removals to assess the risks of producing potentially hazardous compounds. Likewise, the pigments responsible for causing adverse reactions in some patients may be quickly identified to hasten any corresponding treatment. Copyright © 2008 John Wiley & Sons, Ltd. [source] Micro-Raman spectroscopic study of artificially aged natural and dyed woolJOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2008Brenda Doherty Abstract The objective of this study was to evaluate the use of micro-Raman spectroscopy as a non-invasive vibrational spectroscopic technique applied to the examination of wool samples, which may be applied to textile materials of cultural heritage interest. In this work, a selection of wool materials were primarily investigated in their unaged states through the utility of a natural wool reference together with selected samples dyed with different natural colorants, namely woad, weld and madder. The identification of the main modes of vibration of the wool fibre keratin was assessed in all the samples, which aided the determination of the changes within the protein structure, in particular, through the cysteine and peptide cross-linkages brought about by the addition of the dyes that can produce effects similar to degradation. The dye too was assessed importantly to enable its identification through its characteristic scattering or fluorescence emissions on a woollen matrix, as well as to ascertain whether a uniform covering across the surface of the wool was achieved or not. Regarding the artificial degradation of the samples it was possible to observe numerous modifications within the molecular structure of the wool, in particular, within the amide I, CH bending, amide III and S-S stretchings along with the physical photo-yellowing of fibres given by the presence of lipids dispersed across the surface of the wool. The effects of ageing on the dyed samples were also investigated, indicating that many of the bands relative to the colorants were still present, yet so too were numerous vibrations from the wool that also indicated a certain level of stress and degradation to the underlying wool. Copyright © 2008 John Wiley & Sons, Ltd. [source] Micro-Raman characterizations of Pompei'smortarsJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2008M. Castriota Abstract The ancient town of Pompei offers a unique opportunity to study in detail many aspects of the every day life during the Roman early imperial age. The application of micro-Raman spectroscopy can be of great help in performing a reasonably rapid comparative analysis of the mortars, quite useful to ascertain the degree of uniformity of the technical recipes among the various building firms and the eventual technical evolution in the time; moreover, the individuation of minerals of specific geographical origins can give useful information about the extension of commercial intercourses. An example of a micro-Raman investigation on building materials is reported in this work, concerning the analysis of the mortars coming from different points of the wall in the ,The House of the Wedding of Hercules'. Remarkable differences between ancient and modern mortars are found, allowing a discrimination that can be useful in the case of historical building which underwent several restoration works. Copyright © 2008 John Wiley & Sons, Ltd. [source] Raman spectroscopic analysis of azurite blackeningJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2008E. Mattei Abstract Azurite is a basic copper carbonate pigment largely employed in painting realization. The areas painted with azurite are easily alterable and are often less resistant than the other parts of artworks. The azurite alteration in a black pigment, the copper oxide (tenorite), has been studied by micro-Raman spectroscopy. The blackening can be due to thermal or chemical alterations: in the second case the alterations being due to the presence of alkaline conditions. Laser-induced degradation of azurite has been studied as a function of the grain size. The results show that the temperature of the grains decreases as the size increases, and azurite degrades into tenorite only below the critical value of 25 µm. To study the chemical alteration of azurite, the pigment has been applied on the plaster of terracotta samples and analyzed at different pH values by micro-Raman spectroscopy. As opposed to most part of the analytical techniques, it can detect the presence of both azurite and tenorite molecules in the same micro areas, and provides a valuable tool to determine azurite degradation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Micro-Raman study of Zr-substituted Bi4Ti3O12 ceramicsJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2007S. R. Das Abstract We have studied the lattice vibrational modes of Zr-substituted Bi4Ti3O12 ceramics using micro-Raman spectroscopy. Replacement of Zr at the Ti site in the perovskite block is found from the increase in the lattice parameters as a function of Zr contents. Combined X-ray diffraction patterns and Raman analysis suggested less than 40 mole% Zr solubility in Bi4Ti3O12. At 40 mole% of Zr substitution or above, the unreacted monoclinic-phase ZrO2 is observed in the X-ray diffraction patterns and the Raman spectra. The incorporation of Zr in Bi4Ti3O12 reduces the soft mode wavenumber and the transition temperature. Moreover, temperature dependent studies confirmed the ferroelectric to paraelectric transition in Bi4Ti3O12 at about 675 °C. On increasing the Zr content up to 40% on the Ti sites of Bi4Ti3O12, a systematic decrease in the phase transition temperature from 675 to 630 °C was observed. Copyright © 2007 John Wiley & Sons, Ltd. [source] Nanomechanics of single keratin fibres: A Raman study of the ,-helix ,,-sheet transition and the effect of waterJOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2007Raphaël Paquin Abstract The use of micro-Raman spectroscopy, through chemical-bond, nano-scale probes, allows the changes in conformations (,-helix ,,-sheet), chain orientation, breakage of disulfide bonds (20%) and the increase of intra- and inter-chain distances during the application of stress to be distinguished. The combination of micro-Raman spectroscopy and a Universal Fibre Tester allows a quantitative measurement of the extension of chemical bonds in the peptide chain during loading. The nano-structural transformations of keratin during strain of human hair in a dry environment (40,60% relative humidity) and saturated with water have been studied. Water permits the sliding of the chains and decreases the bond energy of the hair. Spectral analyses and 2D correlation are two coherent and independent methods to follow the structural nano-mechanical (Raman) and micro-mechanical (strain/stress) analyses, and confirm the validity of the experimental results, tools and principles used, as well as the agreement with the structural model of keratin fibres described by Chapman and Hearle. Copyright © 2006 John Wiley & Sons, Ltd. [source] Bullous pemphigoid detection by micro-Raman spectroscopy and cluster analysis: structure alterations of proteinsJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2005Erez Azrad Abstract In this study, micro-Raman spectroscopy was used, for the first time, to detect spectral changes between healthy and diseased skin tissues with bullous pemphigoid (BP). The spectral changes provide information about the biochemical alterations between normal skin and blistered and nonblistered regions in samples diagnosed histopathologically as BP. Raman spectra, characterized by many peaks, revealed the molecular composition of the different skin layers, stratum corneum, epidermis and dermis of normal skin. Comparison of spectra monitored at the dermoepidermal junction (DEJ) of healthy skin with those of blisters caused by BP showed evidence for large variations in the amide I and III regions. The alterations of the protein content, amide I and III, are a result of the appearance of immunoglobulin G (IgG) and fibrin, characteristics of BP. Indication for the disease at early stages was obtained from changes in protein content, evidenced in the measured spectra assisted by cluster analysis. The method employed here can contribute to the nearly real-time diagnosis and to a better understanding of the physical and biomolecular processes effected by BP, and might have implications on other skin diseases. Copyright © 2005 John Wiley & Sons, Ltd. [source] Study of the adsorption of benzimidazole and 2-mercaptobenzothiazole on an iron surface by confocal micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2004G. Wang Abstract Benzimidazole (BIMH) and 2-mercaptobenzothiazole (HMBT) dissolved in ethanol were chosen for the investigation of the interaction between organic molecules and surface atoms of iron or iron oxide by confocal micro-Raman spectroscopy. Both BIMH and HMBT show enhanced and highly structured spectra in the 200,1500 cm,1 region when the iron is at a potential of ca ,0.7 to ,0.9 V in a neutral medium. BIMH had a weak interaction with the iron surface in a basic medium but it was chemically adsorbed in a neutral medium. HMBT was chemically adsorbed on the iron via the exocyclic S and N atoms in acidic and neutral solutions, whereas in basic media it was bound electrostatically. Copyright © 2004 John Wiley & Sons, Ltd. [source] Identification of nineteenth century blue and green pigments by in situ x-ray fluorescence and micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8-9 2004F. Rosi Abstract A mural painting by the innovative Italian miniaturist Napoleone Verga (1833,1918) was studied by a model protocol that combines an in situ non-destructive technique with laboratory micro-destructive vibrational investigations. The experimental procedure allowed us to acquire detailed information not only on Verga's palette and painting technique but also on undocumented retouches, using a very restricted number of samples. Copyright © 2004 John Wiley & Sons, Ltd. [source] Bronze Age painted plaster in Mycenaean Greece: a pilot study on the testing and application of micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8-9 2004Ann Brysbaert Abstract Since the first discoveries of Minoan and Mycenaean painted plaster around the end of the 19th and early 20th centuries, iconographic and, to a lesser extent, technological studies have gone hand in hand in order to understand how these prehistoric societies were able to produce some of the earliest and most significant works of art in Bronze Age Europe and the eastern Mediterranean. These paintings claim to be among the first to be executed in the buon fresco technique. Past technological studies employed wet chemical methods, x-ray diffraction (XRD), optical emission spectroscopy and a range of microscopic techniques based on cross-sections of samples in order to investigate these fragmentary paintings. Most of these methods required destructive sampling and this is now, rightly so, very much restricted. Consequently, other non-micro-destructive approaches are being tested at present. Micro-Raman spectroscopy (MRS) has proven more than once its potential for non-destructive analysis of works of art and in archaeology in the recent past. Its application to this early fragmentary material is presented here for the first time. Interesting results were the identification of both organic (indigo) and non-crystalline materials (limonite), which complements the knowledge obtained from traditionally used techniques. Although not without problems (high fluorescence prevented identification of Egyptian Blue), non-destructive MRS yielded results comparable to XRD and provided the first identification of indigo blue on this medium, and can hence be considered very useful in future sample-reducing strategies considering these scarce materials. Copyright © 2004 John Wiley & Sons, Ltd. [source] Pigments and binders in the wall paintings of Santa Maria della Steccata in Parma (Italy): the ultimate technique of ParmigianinoJOURNAL OF RAMAN SPECTROSCOPY, Issue 8-9 2004Danilo Bersani Abstract Micro-Raman spectroscopy and gas chromatography combined with mass spectrometry (GC,MS) were employed to investigate the materials used in the wall paintings by the older Parmigianino (Francesco Mazzola, 1503,1540) on the arch over the main altar in the church of Santa Maria della Steccata in Parma, Italy. The pigments used by the artist and those added by later restorations are characterized by micro-Raman spectroscopy. GC,MS identified the organic binding media in the paint samples and revealed the presence of polysaccharides in the plaster. These investigations may be useful for a comparison with the technique of the young Parmigianino, author of wall paintings in the church of S. Giovanni Evangelista in Parma in the 1520s. Copyright © 2004 John Wiley & Sons, Ltd. [source] The use of micro-Raman spectroscopy in architectural paint analysisJOURNAL OF RAMAN SPECTROSCOPY, Issue 8-9 2004E. Kendix Abstract Architectural paint analysis is an important technique for establishing the palette of historical paint colours, and reconstructing how a room or a facade might have looked at an earlier time. In its simplest form, it has often been achieved by using paint scrapes, which involves revealing a stepped sequence of layers of paint using a blade or solvents. Cross-sections are used as an alternative to, or in combination with, scrapes. Mounted cross-sections can be examined by optical microscopy. Accumulated layers of paint, wallpaper or other applied decorative finishes can be defined from their textures and colours. Knowledge of the identity of the components in paint layers can be used to reconstruct a certain paint and also to date the paint layers. It is demonstrated that micro-Raman spectroscopy combined with optical microscopy and low-vacuum scanning electron microscopy,energy-dispersive spectrometry are versatile tools for the characterization of pigments and fillers in cross-sections from architectural decorations. The paper gives an example of the examination of an interior decoration from a historical building. Copyright © 2004 John Wiley & Sons, Ltd. [source] Characterization of CaCO3 hydrates by micro-Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2002M. M. Tlili The Raman spectra of the three varieties of hydrated calcium carbonate, monohydrate, hexahydrate and ,amorphous,' are reported for the first time and discussed according to the already known crystal structures. The transformation by dehydration of these hydrated phases into the usual anhydrous forms was followed by in situ micro-Raman spectroscopy. It is shown that the dehydration of the hexahydrate proceeds through the formation of the ,amorphous' phase. The latter is better described as microcrystalline monohydrate. Copyright © 2002 John Wiley & Sons, Ltd. [source] Combining two structural techniques on the micrometer scale: micro-XAS and micro-Raman spectroscopyJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2007V. Briois X-ray absorption and Raman spectroscopies are complementary in the sense that both give very precise information about the local structure of a sample, both are not restricted to crystalline materials, and in both cases the volumes of the material probed are similar. The X-ray technique has the advantage of being element- and orbital-selective, and sensitive to orientational effects owing to polarization selection rules. In many cases, however, its analysis can present some ambiguity. Combining the two techniques on a micrometer scale could therefore be a very powerful method structurally. In this paper the experimental set-up developed at the LUCIA beamline and its application to a natural mineral are described. [source] Effect of B2O3 Addition on the Thermal Stability of Barium Phosphate Glasses for Optical Fiber DevicesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2004Takashi Harada The effect of B2O3 addition on the thermal stability of BaO,P2O5 glasses is studied by differential thermal analysis (DTA), X-ray diffraction (XRD) analysis, scanning electron microscopy, and micro-Raman spectroscopy. The difference between glass-transition and onset-crystallization temperatures increases monotonically with increasing B2O3 concentration. The DTA result reveals that no exothermic peak due to surface crystallization exists in the BaO,P2O5 glass doped with 3 mol% B2O3. A single-mode BaO,P2O5 -B2O3 glass fiber could be fabricated by a rod-in-tube technique. The modification of glass structure due to B2O3 addition is qualitatively discussed. [source] HRTEM, Raman and optical study of CdS1,xSex nanocrystals embedded in silicate glassPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 13 2004V. Bellani Abstract We studied CdS1,xSex nanocrystals embedded in a silicate glass by means of complementary techniques like high resolution transmission electron microscopy (HRTEM), micro-Raman spectroscopy and optical transmission and reflectivity. Transmission Electron Microscopy gives complete information on crystallization and size distribution of the nanocrystals wile Raman scattering is particularly useful in the determination of the composition of the nanocrystals for low-concentration or small-crystallite size composite. Having the size distribution and composition of the nanocrystals we have explained the transmission spectra of the studied samples. Optical transmission spectra evidence the quantization of the electronic states of the nanoparticles system with a size distribution described by a Gaussian function. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Raman scattering analysis of GaN with various dislocation densitiesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008T. Kitamura Abstract We characterized GaN crystals with various dislocation densities by micro-Raman spectroscopy. Defects and Strain for the GaN layer were examined through measurements of the Raman shift and the width of the TO phonon bands. The broadening of Raman bands in GaN crystals occurred as the dislocation density increased. The up-shift of the peak frequencies corresponding to compressive strain was observed for the heteroepitaxial samples grown by MOCVD and MBE. The in-plane distribution of defects and strain in epilayers with various dislocation densities was also examined by Raman mapping. The Raman maps showed that the examined phonon frequency and band width in samples fluctuated spatially. The increase of dislocation density in GaN epilayers induced not only the broadening of Raman bands but also increase of fluctuation. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||