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1.
Raman spectra have been obtained from a Madonna and Child tondo painting, known as the de Brécy Tondo. Despite the provision
of only a small number of microscopic samples, definitive spectra were obtained from mineral pigments. From one specimen,
spectra of an organic binder enabled the consideration of several possibilities to be accomplished and a suggestion proposed
for the medium. In another specimen the identification of the spectral signatures of Prussian blue, which was only synthesised
some 200 years after the predicated date of execution of the painting, indicated that some unrecorded restoration had been
undertaken later in the painting’s history. Research* carried out on this tondo from 1987 to 1991 indicated the probability
that it is the work of Raphael, a conclusion supported by further research recently undertaken on the provenance. The stylistic
similarity of the tondo to Raphael’s Sistine Madonna is very clear; the pigments identified in this analysis are consistent
with a Renaissance attribution for the de Brécy Tondo.
*Dr Murdoch Lothian, The Methods Employed to Provenance and to Attribute Putative Works by Raphael, Ph.D. Thesis, 1991. 相似文献
2.
Raman micro-spectroscopy has been used for the identification of the pigments used by the Spanish painter Diego Velázquez (1599–1650), considered one of the greatest painters in art history. The set of cross-sectional samples studied belongs to paintings of the Museo del Prado collection and correspond to the three known periods of the artist's activity. We have obtained information on the chemical composition and crystal structure of the pigments used for various colours. The results are consistent with previous elemental composition determined by other analytical methods. 相似文献
3.
Petr Vítek Jan Jehli?ka Howell G. M. Edwards Kate?ina Osterrothová 《Analytical and bioanalytical chemistry》2009,393(8):1967-1975
Since evaporitic rocks on the Martian surface could (or still can) serve as potential habitats for microbial life on Mars,
there is a reasonable possibility that these rocks may sustain molecular remnants as evidence for the presence of extinct
or extant living organisms on Mars and that β-carotene could be a suitable biomarker. In this paper, Raman microspectrometry
was tested as a nondestructive method of determining the lowest detectable β-carotene content in experimentally prepared evaporitic
matrices—namely, gypsum, halite and epsomite. Two excitation wavelengths were compared—514.5 nm, because of the resonance
Raman enhancement in the carotenoid analysis, and 785 nm, as a more universal wavelength now much used in the detection of
biomolecules terrestrially. Mixtures were measured directly as well as with a laser beam penetrating the crystals of gypsum
and epsomite. We have obtained β-carotene signals at the 0.1 to 10 mg kg−1 level—the number of registered β-carotene Raman bands differed depending on the particular mineral matrix and the excitation
wavelength. Concentrations of β-carotene of about one order of magnitude higher were identified when analysed through single
crystals of gypsum and epsomite, respectively. 相似文献
4.
A Raman spectroscopic study was carried out on water in gelatin at 4% w/v in gel (25 °C) and sol (40–60 °C) states at various
concentrations (0.5, 1, 5, 10 and 15 mM) of anionic surfactant, sodium dodecyl sulfate (SDS). The in-phase collective stretching
mode vibration of hydrogen-bonded -OH oscillators, centered around 3250 cm−1 in a tetrahedral network of water molecules, was observed to be significantly affected by temperature and the presence of
SDS. According to our observation this may be due to the thinning of the hydration water around the gelatin molecules due
to strong thermal agitation. The peak center of the collective bands of water decreased linearly with SDS concentration in
the gel state which implied that with the increase in concentration of SDS, the -OH oscillators gradually lost their attachment
to gelatin chains and were replaced by SDS molecules. Ultimately this resulted in a thinning of the hydration layer around
the gelatin and the oscillation frequency of -OH oscillators moved towards 3250 cm−1 at 1 mM SDS concentration resulting in increased coupling of -OH oscillators to form the tetrahedral network at the critical
micelle concentration (cmc) of SDS. The variation in the peak amplitudes and the systematic reversal of their trend about
the cmc axis was surprising. At 40 °C the amplitude of the peak at 3250 cm−1 increased drastically due to a possible coil expansion by about 7–8% which accommodated more interstitial water into the
pseudonetwork leading to an increase in the number of nearest neighbors and for about 6% increase in the C value. However, at the cmc the peak amplitude was observed to be independent of temperature. Continuous shifting of the peak
center and full width at half-maxima towards lower values was observed with increasing SDS concentrations in the gel state.
Received: 28 September 1998 Accepted in revised form: 8 March 1999 相似文献
5.
A method for calibrating Raman intensities of diluted aqueous solutions, based on the integrated intensity of the OH stretching bands of liquid water as an external intensity standard, is described and used to obtain a difference spectrum that reveals intensity changes mainly due to the intermolecular interaction between two solutes. The method is applied to trimethyl-β-cyclodextrin in sodium decanoate aqueous solutions. The difference between the interaction spectra above and below the critical micellar concentration of sodium decanoate, in the CH stretching region between 2700 and 3100 cm−1, shows an intensity increase of the CH stretching bands for trimethyl-β-cyclodextrin above the critical micellar concentration of sodium decanoate, whereas β-cyclodextrin is relatively insensitive to the presence of decanoate ion micelles in aqueous solution. 相似文献
6.
Howell G. M. Edwards 《Analytical and bioanalytical chemistry》2010,397(7):2677-2683
The vibrational infrared spectroscopic analysis of an important historical necklace of 102 beads that are purported to be
made of amber indicated strong signal characteristics of cellulose nitrate with dark green-coloured areas of a naphthylamine
dye. Confocal Raman depth-profiling spectroscopy using a 785-nm laser excitation, a novel application first applied here for
the analysis of inclusions in amber resin, confirmed that the beads were amber resin and that residues of cellulose nitrate,
camphor plasticiser and a naphthylamine dyestuff were present in surface cracks and inclusions in the bead matrix. The bead
stringing material was confirmed as cellulose, which was stained green in part with the dyestuff. Comparison of the Raman
spectra of the amber beads with a resin database suggested that the amber was sourced from Northern England. The scientific
evidence supports the stylistic opinion that the necklace is an important example that could date from the 19th Century and
that efforts had been made to coat it with a synthetic dyed polymer; this provides a rather unusual example of the chemical
masking of a genuine article—a procedure that renders the article of particular interest. 相似文献
7.
In a recent article we showed that the 2ν(3) transition of CO(2) gives rise to a Raman spectrum that is almost entirely depolarized [M. Chrysos, I. A. Verzhbitskiy, F. Rachet, and A. P. Kouzov, J. Chem. Phys. 134, 044318 (2011)]. In the present article, we go further forward in the study of this overtone by reporting a first-principles shape analysis of its depolarized spectrum at room temperature. As a first step in our analysis, a model assuming isolated Lorentzian line shapes was applied, which at low gas densities turns out to be sufficient for qualitative conclusions. As the next step, a sophisticated approach was developed on the basis of the extended strong-collision model in order to properly account for the heavy line mixing between rotational lines. Whereas a marked deviation between model and measured spectra was observed upon application of the simpler model, striking agreement even at the highest CO(2) density was found on applying the sophisticated one. Accurate calculated data were used for the rotational line broadening coefficients without resort to arbitrary parameters. Values for the vibrational shift scaling linearly with the density of the gas are given. 相似文献
8.
9.
Silmarilly Bahfenne Ray L. Frost 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(2):637-639
Raman spectroscopy has been sued to study the antimony containing mineral roméite Ca2Sb2O6(OH,F,O) from three different origins. Roméite is a calcium antimonate mineral of the pyrochlore group. An intense Raman band at ~518 cm?1 for roméite is assigned to the SbO ν1 symmetric stretching mode and the band at 466 cm?1 to the SbO ν3 antisymmetric stretching mode. The Raman band at 303 cm?1 is attributed to the OSbO bending mode. Some variation in band positions is observed and is attributed to the variation in composition between the three mineral samples. 相似文献
10.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1993,49(13-14):2027-2038
Raman spectroscopy has been used to obtain thermal phase transition profiles for recombinant particles composed of 1,2-dipalmitoylphosphatidylcholine (DPPC) and apolipoprotein A—I. Comparison of these profiles with unilamellar vesicles of DPPC indicates that lateral packing of DPPC acyl chains is tighter in recombinant DPPC/apolipoporotein A—I particles than in uncomplexed lipid of unilamellar vesicles. Consequently, the magnitude of the entropy change associated with acyl chain melting in the recombinants at the main lipid phase transition is almost twice that of unilamellar DPPC. In addition, a second phase transition has been observed for the DPPC/apolipoprotein A—I complex and has been assigned to the acyl chain melting of DPPC molecules which are bound to the apolipoprotein annulus on the periphery of the discoidal complexes. A combination of results from Raman spectroscopy, electron micrograph measurements and chemical analysis leads to the conclusion that these protein-bound lipids, the “boundary layer”, account for about 20% of the total lipid in the recombinant material. Calculations indicate that there are about 55 protein-bound lipid molecules per apolipoprotein A—I molecule in the DPPC/apolipoprotein A—I discoidal complexes prepared for this study. 相似文献
11.
Ancient biodeterioration: an FT–Raman spectroscopic study of mammoth and elephant ivory 总被引:1,自引:0,他引:1
Edwards HG Jorge Villar SE Nik Hassan NF Arya N O'Connor S Charlton DM 《Analytical and bioanalytical chemistry》2005,383(4):713-720
Raman spectra of mammoth ivory specimens have been recorded using near-infrared excitation, and comparisons made with modern
Asian and African elephant ivories. Whereas the most ancient mammoth ivory (60–65 ky) showed no evidence for an organic collagen
component, more recent samples of mammoth ivory indicated that some preservation had occurred, although with biodeterioration
of the protein structure exhibited by the amide I and III bands in the 1200–1700 cm−1 region of the Raman spectrum. The consequent difficulties encountered when applying chemometrics methods to ancient ivory
analysis (which are successful for modern specimens) are noted. In the most ancient mammoth ivory specimens, which are extensively
fragmented, evidence of mineralization is seen, with the production of gypsum, calcite and limonite; Raman microscopic analysis
of crystalline material inside the fissures of the mammoth ivory shows the presence of gypsum as well as cyanobacterial colonisation.
The application of Raman spectroscopy to the nondestructive analysis of archaeological materials in order to gain information
of relevance to their preservation or restoration is highlighted. 相似文献
12.
Frost RL Cejka J Bostrom T Weier M Martens W 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(5):1220-1227
Raman spectra at 298 and 77K and infrared spectra of the uranyl sulfate mineral zippeite from Jáchymov (Joachimsthal), Czech Republic, K(0.6)(H(3)O)0.4[(UO(2))6(SO(4))3(OH)7].8H2O, were studied. Observed bands were tentatively attributed to the (UO(2))2+ and (SO(4))2- stretching and bending vibrations, the OH stretching vibrations of water molecules, hydroxyls and oxonium ions, and H(2)O, oxonium, and delta U-OH bending vibrations. Empirical relations were used for the calculation of U-O bond lengths in uranyl R (A)=f(nu(3) or nu(1)(UO(2))2+). Calculated U-O bond lengths are in agreement with U-O bond lengths from the single crystal structure analysis and those inferred for uranyl anion sheet topology of uranyl pentagonal dipyramidal coordination polyhedra. The number of observed bands supports the conclusion from single crystal structure analysis that at least two symmetrically distinct U6+ (in uranyls) and S6+ (in sulfates), water molecules and hydroxyls may be present in the crystal structure of the zippeite studied. Strong to very weak hydrogen bonds present in the crystal structure of zippeite studied were inferred from the IR spectra. 相似文献
13.
Baddour-Hadjean R Smirnov MB Smirnov KS Kazimirov VY Gallardo-Amores JM Amador U Arroyo-de Dompablo ME Pereira-Ramos JP 《Inorganic chemistry》2012,51(5):3194-3201
We report here the Raman spectrum and lattice dynamics study of a well-crystallized β-V(2)O(5) material prepared via a high-temperature/high-pressure (HT/HP) route, using α-V(2)O(5) as the precursor. Periodic quantum-chemical density functional theory calculations show good agreement with the experimental results and allow one to assign the observed spectral features to specific vibrational modes in the β-V(2)O(5) polymorph. Key structure-spectrum relationships are extracted from comparative analysis of the vibrational states of the β-V(2)O(5) and α-V(2)O(5) structures, and spectral patterns specific to the basic units of the two V(2)O(5) phases are proposed for the first time. Such results open the way for the use of Raman spectroscopy for the structural characterization of vanadium oxide-based host lattices of interest in the field of lithium batteries and help us to greatly understand the atomistic mechanism involved in the α-to-β phase transition of vanadium pentoxide. 相似文献
14.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1994,50(11):2011-2017
The diimide hydrogenation of cis-polybutadiene is studied. p-Toluenesulfonylhydrazide is used to fully and partially hydrogenate cis-polybutadiene. The microstructure and hydrogenation of the samples obtained are subsequently studied by FT Raman spectroscopy. Cis—trans isomerization is found to take place during the reaction. A mechanism of isomerization and hydrogenation is also proposed. 相似文献
15.
16.
In this study lanthanum trilactate was prepared by neutralization reaction of lactic acid and lanthanum oxide, purified and identified by X-ray powder diffraction. Infrared spectra (Mid-IR region 4000–650 cm−1) and Raman spectra (Stokes region 4000–100 cm−1) of the high quality crystalline samples have been recorded and presented for the first time. For comparison DFT calculations were performed using Gaussian 09 D.01 and agreement between predicted and measured spectral data has been achieved. Acquired information can be utilized for substance identification for example in various industrial applications or in biological systems. 相似文献
17.
Wu Zhenwei Ran Rui Ma Yue Wu Xiaodong Si Zhichun Weng Duan 《Research on Chemical Intermediates》2019,45(3):1309-1325
Research on Chemical Intermediates - A series of Cu–SAPO-34 catalysts with different copper contents were prepared using a modified ion-exchange method, i.e., impregnation–activation.... 相似文献
18.
Carmona P Molina M Calero M Bermejo-Pareja F Martínez-Martín P Alvarez I Toledano A 《Analytical and bioanalytical chemistry》2012,402(6):2015-2021
Peripheral mononuclear leukocytes from Alzheimer’s disease (AD) patients were analyzed by infrared spectroscopy and their
spectroscopic properties were compared with those from age-matched healthy controls. Two-dimensional correlation analysis
of mean spectra measured at various disease stages shows that the protein secondary structure from AD patients involves β-sheet
enrichment and carbonyl intensity increase relative to healthy controls. The area percentages of β-sheets, which were obtained
by using a peak ratio second-derivative spectral treatment, were used for receiver operating characteristic (ROC) analysis
to distinguish between patients with AD and age-matched healthy controls. The critical concentration and area under the curve
(AUC) were determined by this curve analysis which showed a good performance for this quantitative assay. The results were
90% sensitivity and 90.5% specificity for determinations involving mild and moderate AD patients, and 82.1% sensitivity and
90.5% specificity for determinations involving patients at the three AD stages (mild, moderate, and severe). The AUC was greater
than 0.85 in both scenarios. Taken together these results show that healthy controls are distinguished from mild and moderate
AD patients better than from patients with severe disease and suggest that this infrared analysis is a promising strategy
for AD diagnostics. 相似文献
19.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1988,44(10):1007-1010
In this work, it is shown that careful contour analysis of the symmetric stretching mode of H2PO−4 of ammonium dihydrogen phosphate may reveal certain structural information as the solution varies from the unsaturated state to the supersaturated state. Both the concentration and temperature dependent cases are demonstrated. It is seen that in solutions there can be varying compositions of monomer, dimeric and polymeric aggregates of H2PO−4 depending on the concentration and temperature. Apparently, there is a thermodynamic point above which the polymeric aggregates cannot be in thermodynamic equilibrium with the monomeric or dimeric species and the solution is therefore thermodynamically unstable. There is also no discontinuity in the half band width and peak frequency as the solution reaches supersaturation consistent with the refractive index and electrical conductivity measurements. 相似文献
20.
The binding characteristics of neutral red (NR) with DNA were investigated by fluorescence spectrometry. Chemometrics approach as singular value decomposition (SVD) was used to evaluate the number of spectral species in the drug-DNA binding process, and then the intrinsic binding constant of 1.6 × 104 in base pairs and the binding site number of 0.97 were obtained from the Scatchard plot. 相似文献