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Spectroscopic Study (spectroscopic + study)
Kinds of Spectroscopic Study Selected AbstractsThioxoethenylidene C2S: A Matrix - Spectroscopic StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2004Günther Maier Abstract Thioxoethenylidene C2S (5), known for its high abundance in interstellar space, has been generated by irradiation of C3S2 (4) and C3OS (6) in an argon matrix at 10 K. Its structural elucidation is based on comparison of the experimental and calculated IR and UV spectra. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] In Situ UV Raman Spectroscopic Study on the Synthesis Mechanism of AlPO-5,ANGEWANDTE CHEMIE, Issue 46 2009Fengtao Fan Ein weiteres Puzzleteil: Der Mechanismus der AlPO-5-Synthese wurde durch In-situ-UV-Raman-Spektroskopie in Verbindung mit der Fenton-Reaktion auf molekularer Ebene untersucht. Die Ergebnisse geben Einblick in die Rolle des Templats bei der Kanalbildung und ermöglichen die Identifizierung der am Gerüstaufbau beteiligten Bausteine. [source] Solution-State 15N NMR Spectroscopic Study of ,-C-Phycocyanin: Implications for the Structure of the Chromophore-Binding Pocket of the Cyanobacterial Phytochrome Cph1CHEMBIOCHEM, Issue 18 2007Janina Hahn Abstract The detailed structure of the chromophore-binding pocket in phytochrome proteins and the structural changes associated with its photocycle are still matters of debate. Insight into the structure and dynamics of the binding pocket has been gained through the comparison of a 15N NMR spectrum of ,-C-phycocyanin, which is often used as a model system for the study of phytochromes, with the previously described 15N NMR spectrum of the cyanobacterial phytochrome Cph1. The former spectrum supports the hypothesis that all four nitrogen atoms of the ,-C-phycocyanin chromophore are protonated, in analogy with the proposed protonation state for the Pr and Pfr forms of Cph1. The spectra show that the chromophores in both proteins exhibit a distinct dynamic behavior, as also indicated by a NOESY spectrum of Cph1. Finally, stereochemical arguments and a Cph1 homology model support the hypothesis that the chromophore in Cph1 is most likely in the ZZZssa conformation in the Pr form of the protein. [source] ChemInform Abstract: A 119Sn Moessbauer and 45Sc Solid State NMR Spectroscopic Study of the Stannides ScTSn (T: Ni, Pd, Pt).CHEMINFORM, Issue 4 2009Thomas Harmening Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Spectroscopic Study of YBa3B9O18, an Interesting Material Containing a Six-Membered Borate Ring.CHEMINFORM, Issue 51 2008Enrique J. Baran Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] NMR Spectroscopic Study of Xenon Fluorides in the Gas Phase and XeF2 in the Solid State.CHEMINFORM, Issue 37 2004Michael Gerken No abstract is available for this article. [source] Phosphine Ligands in the Palladium-Catalysed Methoxycarbonylation of Ethene: Insights into the Catalytic Cycle through an HP,NMR Spectroscopic StudyCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2010Verónica de, la Fuente Dipl.-Chem. Abstract Novel cis -1,2-bis(di- tert -butyl-phosphinomethyl) carbocyclic ligands 6,9 have been prepared and the corresponding palladium complexes [Pd(O3SCH3)(L-L)][O3SCH3] (L- L=diphosphine) 32,35 synthesised and characterised by NMR spectroscopy and X-ray diffraction. These diphosphine ligands give very active catalysts for the palladium-catalysed methoxycarbonylation of ethene. The activity varies with the size of the carbocyclic backbone, ligands 7 and 9, containing four- and six-membered ring backbones giving more active systems. The acid used as co-catalyst has a strong influence on the activity, with excess trifluoroacetic acid affording the highest conversion, whereas excess methyl sulfonic acid inhibits the catalytic system. An in operando NMR spectroscopic mechanistic study has established the catalytic cycle and resting state of the catalyst under operating reaction conditions. Although the catalysis follows the hydride pathway, the resting state is shown to be the hydride precursor complex [Pd(O3SCH3)(L- L)][O3SCH3], which demonstrates that an isolable/detectable hydride complex is not a prerequisite for this mechanism. [source] A Time-Resolved Spectroscopic Study of the Bichromophoric Phototrigger 3,,5,-Dimethoxybenzoin Diethyl Phosphate: Interaction Between the Two Chromophores Determines the Reaction PathwayCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2010Chensheng Ma Dr. Abstract 3,,5,-Dimethoxybenzoin (DMB) is a bichromophoric system that has widespread application as a highly efficient photoremovable protecting group (PRPG) for the release of diverse functional groups. The photodeprotection of DMB phototriggers is remarkably clean, and is accompanied by the formation of a biologically benign cyclization product, 3,,5,-dimethoxybenzofuran (DMBF). The underlying mechanism of the DMB deprotection and cyclization has, however, until now remained unclear. Femtosecond transient absorption (fs-TA) spectroscopy and nanosecond time-resolved resonance Raman (ns-TR3) spectroscopy were employed to detect the transient species directly, and examine the dynamic transformations involved in the primary photoreactions for DMB diethyl phosphate (DMBDP) in acetonitrile (CH3CN). To assess the electronic character and the role played by the individual sub-chromophore, that is, the benzoyl, and the di- meta -methoxybenzylic moieties, for the DMBDP deprotection, comparative fs-TA measurements were also carried out for the reference compounds diethyl phosphate acetophenone (DPAP), and 3,,5,-dimethoxybenzylic diethyl phosphate (DMBnDP) in the same solvent. Comparison of the fs-TA spectra reveals that the photoexcited DMBDP exhibits distinctly different spectral character and dynamic evolution from those of the reference compounds. This fact, combined with the related steady-state spectral and density functional theoretical results, strongly suggests the presence in DMBDP of a significant interaction between the two sub-chromophores, and that this interaction plays a governing role in determining the nature of the photoexcitation and the reaction channel of the subsequent photophysical and photochemical transformations. The ns-TR3 results and their correlation with the fs-TA spectra and dynamics provide evidence for a novel concerted deprotection,cyclization mechanism for DMBDP in CH3CN. By monitoring the direct generation of the transient DMBF product, the cyclization time constant was determined unequivocally to be ,1,ns. This indicates that there is little relevance for the long-lived intermediates (>10,ns) in giving the DMBF product, and excludes the stepwise mechanism proposed in the literature as the major pathway for the DMB cyclization reaction. This work provides important new insights into the origin of the 3,,5,-dimethoxy substitution effect for the DMB photodeprotection. It also helps to clarify the many different views presented in previous mechanistic studies of the DMB PRPGs. In addition to this, our fs-TA results on the reference compound DMBnDP in CH3CN provide the first direct observation (to the best of our knowledge) showing the predominance of a prompt (,2,ps) heterolytic bond cleavage after photoexcitation of meta -methoxybenzylic compounds. This provides insight into the long-term controversies about the photoinitiated dissociation mode of related substituted benzylic compounds. [source] A Spectroscopic Study of the Reduction of Geometrically Restrained ViologensCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2007Andrew Abstract A small series of N,N,-dimethyl-4,4,-bipyridinium dication derivatives (commonly known as viologens) has been synthesized and fully characterized; a short dialkoxy tether attached at the 3,3,-positions is used to alter the central dihedral angle. These angles were determined by both single-crystal X-ray diffraction and by computational studies made for the dication, radical cation, and neutral species in a solvent reservoir. The dihedral angle derived for the dication controls the first reduction potential, whereas the geometry of the resultant ,-radical cation determines the magnitude of the second reduction potential. The optical absorption spectra recorded for the various species, and especially those of the radical cations, and the EPR spectral parameters of the ,-radical cations also depend on the molecular geometry. In particular, the central dihedral angle influences the spin density distribution around the aromatic nucleus and, by way of comparison to the parent viologen, it has been possible to resolve the angle dependence from the inherent inductive effect of the strap. These results are considered in terms of the degree of electronic communication between the two aromatic rings, as controlled by the length of the tether. [source] Interaction of Cytidine 5,-Monophosphate with Au(111): An In Situ Infrared Spectroscopic StudyCHEMPHYSCHEM, Issue 9-10 2009Thomas Doneux Dr. Abstract Attracted to gold: The interaction of cytidine 5,-monophosphate (CMP) with gold surfaces is studied at the Au(111) | aqueous solution interface. In situ infrared spectroscopy studies show that cytidine 5,-monophosphate is chemisorbed on Au(111) through the N3 atom of the pyrimidine ring (see picture). The interaction of cytidine 5,-monophosphate (CMP) with gold surfaces is studied by means of in situ infrared spectroscopy and cyclic voltammetry at the Au(111) | aqueous solution interface. Similar to other nucleic acid components, cytidine 5,-monophosphate is chemisorbed on the surface at positive potentials, and the amount of adsorbed CMP increases with the potential. Subtractively normalized interfacial Fourier-transform infrared spectroscopy (SNIFTIRS) is used to identify the adsorbed and desorbed species. Upon electrochemical desorption, the molecules released in solution are unprotonated on the N3 atom. Striking similarities are found between the spectrum of adsorbed CMP and the solution spectrum of protonated CMP. The origin of such similarities is discussed. The results strongly suggest that chemisorption occurs through the N3 atom of the pyrimidine ring. A comparison is drawn with cytidine, whose electrochemical and spectroscopic behaviors are also investigated. [source] Spectroscopic Study on Interaction of , -Cyclodextrin with Triprolidine HydrochlorideCHINESE JOURNAL OF CHEMISTRY, Issue 5 2006Syed Mashhood Ali Abstract The complexation of triprolidine hydrochloride (TRP) and , -cyclodextrin (, -CD) in deuterium oxide was investigated by 400 MHz 1H NMR spectroscopy. The 800 MHz 2D ROESY data revealed that two 1:1 and one 2:1 , -CD-TRP inclusion complexes were formed. Both aromatic moieties (p -tolyl and pyridyl ring) has entered into the , -CD cavity, confirming the existence of two different equilibria for 1:1 inclusion complexes in which p -tolyl ring of the guest is more tightly held by the host cavity. The ROE intermolecular interactions provided the plausible structures of these 1:1 and 2:1 stoichiometric inclusion complexes of , -CD-triprolidine hydrochloride in solution. [source] Spectroscopic study of the penetration depth of grafted polystyrene onto poly(tetrafluoroethylene- co -perfluoropropylvinylether) substrates.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2002Abstract This study concerns the radiation grafting of styrene onto poly(tetrafluoroethylene- co -perfluoropropylvinylether) (PFA) substrates and the penetration depth of the graft. Grafting was obtained by the simultaneous irradiation method, and the spectroscopic analysis was made with the micro-Raman technique. Effects of grafting conditions such as the type of solvent, dose rate, and irradiation dose on the grafting yield were investigated. Of the different solvents used, the most efficient in terms of increasing grafting yield were dichloromethane, benzene, and methanol, respectively. A mixture of methanol and dichloromethane used as a solvent for styrene achieved a higher degree of grafting and concentration of grafted polystyrene onto the surface of PFA substrates than solutions of the monomer in the separate solvents. The degree of grafting increased with increasing radiation dose up to 500 kGy, stabilizing above this dose. However, the grafting yield decreased with an increase in the dose rate. The increase in the overall grafting yield was accompanied by a proportional increase in the penetration depth of the grafts into the substrate. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3191,3199, 2002 [source] Spectroscopic study of the long-period dust-producing WC7pd+O9 binary HD 192641MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2005L. Lefèvre ABSTRACT We present the results of an optical spectroscopic study of the massive Wolf,Rayet (WR) binary HD 192641 = WR 137. These 1986,2000 data cover the dust-formation maximum in 1997. Combining all available measurements of radial velocities, we derive, for the first time, a spectroscopic orbit with period 4766 ± 66 d (13.05 ± 0.18 yr). The resulting masses, adopting i= 67 °, are MO= 20 ± 2 M, for the O component and MWR= 4.4 ± 1.5 M, for the WR component. These appear, respectively, approximately normal and on the low side for the given spectral types. Analysis of the intense multisite spectroscopic monitoring in 1999 shows that the C iii,5696 and C iv,,5802/12 lines have the highest intrinsic variability levels. The periodogram analysis yields a small-amplitude modulation in the absorption troughs of the C iv,,5802/12 and He i,5876 lines with a period of 0.83 d, which could be related either to pulsations or large-scale rotating structures as seen in the WN4 star EZ Canis Majoris (WR 6). Wavelet analysis of the strong emission lines of C iii,5696 and C iv,,5802/12 enabled us to isolate and follow for several hours small structures (emission subpeaks) associated with density enhancements within the wind of the Wolf,Rayet star. Cross-correlating the variability patterns seen in different lines, we find a weak but significant correlation between the variability in emission lines with different ionization potentials, i.e. in lines formed at different distances from the WR stellar core. Adopting a , wind-velocity law, from the motion of individual subpeaks we find ,, 5, which is significantly larger than the canonical value ,, 1 found in O star winds. [source] Spectroscopic study of the physical properties making trehalose a stabilizing and shelf life extending compound in food industryQUALITY ASSURANCE & SAFETY OF CROPS & FOOD, Issue 2 2010S. Magazù Abstract Introduction Trehalose, a glass-forming bioprotectant disaccharide, has been demonstrated to possess significant potential within the food industry. It does not interact with reactive molecules such as amino groups from peptides and proteins, preventing the degradation and aggregation due to Maillard reactions. Objective This paper aims to review at the molecular level the effects of trehalose on the structural and dynamical properties of water and on protein to highlight the stabilization and conservation properties on food products. Results and Conclusions The experimental findings presented show that water molecules are arranged in presence of trehalose in a particular configuration which avoids ice formation, so limiting damage due to freezing and cooling. On the other hand, homologous disaccharides, and trehalose to a greater extent, slow down the dynamics of water with a significant influence on the biological activity. These results imply that trehalose has a greater ability to bind volatile substances and deliver superior bioprotective effectiveness. Furthermore trehalose is shown to be incapable of taking part in the denaturation process of lysozyme under thermal stress. [source] Spectroscopic study on structure of horseradish peroxidase in water and dimethyl sulfoxide mixtureBIOPOLYMERS, Issue 2 2002Yasushi Maeda Abstract The structure of horseradish peroxidase (HRP) in phosphate buffered saline (PBS)/dimethyl sulfoxide (DMSO) mixed solvents at different compositions is investigated by IR, electronic absorption, and fluorescence spectroscopies. The fluorescence spectra and the amide I spectra of ferric HRP [HRP(Fe3+)] show that overall structural changes are relatively small up to 60% DMSO. Although the amide I band of HRP(Fe3+) shows a gradual change in the secondary structure and a decrease in the contents of , helices, its fluorescence spectra indicate that the distance between the heme and Trp173 is almost constant. In contrast, the changes in the positions of the Soret bands for resting HRP(Fe3+) and catalytic intermediates (compounds I and II) and the IR spectra at the CO stretching vibration mode of carbonyl ferrous HRP [HRP(Fe2+)-CO] show that the microenvironment in the distal heme pocket is altered, even with low DMSO contents. The large reduction of the catalytic activity of HRP even at low DMSO contents can be attributed to the structural transition in the distal heme pocket. In PBS/DMSO mixtures containing more than 70 vol % DMSO, HRP undergoes large structural changes, including a large loss of the secondary structure and a dissociation of the heme from the apoprotein. The presence of the components of the amide I band that can be assigned to strongly hydrogen bonding amide CO groups at 1616 and 1684 cm,1 suggests that the denatured HRP may aggregate through strong hydrogen bonds. © 2002 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 67: 107,112, 2002 [source] Structural and spectroscopic study of Mg13.4(OH)6(HVO4)2(H0.2VO4)6CRYSTAL RESEARCH AND TECHNOLOGY, Issue 11 2008Abstract Single-crystals of the polar compound magnesium hydrogen vanadate(V), Mg13.4(OH)6(HVO4)2(H0.2VO4)6, were synthesized hydrothermally. It represents the first hydrogen vanadate(V) among inorganic compounds. Its structure was determined by single-crystal X-ray diffraction [space group P 63mc, a = 12.9096(2), c = 5.0755(1) Å, V = 732.55(2) ų, Z = 1]. The crystal structure of Mg13.4(OH)6(HVO4)2(H0.2VO4)6 consists of well separated, vacancy-interrupted chains of face sharing Mg2O6 octahedra, with short Mg2,Mg2 distances of 2.537(1) Å, embedded in a porous magnesium vanadate 3D framework having the topology of the zeolite cancrinite. All three hydrogen positions in the structure were confirmed by FTIR spectroscopy. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Highly Symmetrical Tetranuclear Cluster Complexes Supported by p - tert -Butylsulfonylcalix[4]arene as a Cluster-Forming LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006Takashi Kajiwara Abstract Square-planar tetranuclear clusters [M4(L)(AcO)4(,4 -OH)], (M = MnII, CoII, and NiII) are synthesized using tetra-anionic p - tert -butylsulfonylcalix[4]arene (L4,) as a cluster-forming ligand. Three complexes are crystallographically isostructural, being crystallized in the triclinic crystal system with space group P. The calix[4]arene acts as a tetrakis fac -tridentate ligand through four phenoxo and four sulfonyl oxygen atoms to form square arrangement of four metal ions, which are further bridged by four chelating acetate ions and one hydroxo ion in a ,4 manner to complete the hexacoordination of each metal center. Although the whole molecule of each complex is crystallographically independent, the molecule is highly symmetrical with a pseudo-four-fold axis lying on the ,4 -OH, group. The tetranuclear clusters are stable enough to maintain the core structures even in highly dilute solution (,10 ,M), which was confirmed by mass spectroscopic study, however, bridging acetates were easily exchanged by other carboxylate chelates to form derivatives such as [M4(L)(BzO)4(OH)],. Metal,metal interactions were investigated by means of magnetic susceptibility, and it was revealed that both ferro- and antiferromagnetic interactions occur in the NiII complex depending on the bridging angles of Ni,O,Ni. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] A spectroscopic study of the reaction of NAMI, a novel ruthenium(III)anti-neoplastic complex, with bovine serum albuminFEBS JOURNAL, Issue 4 2000Luigi Messori The reaction of Na[transRuCl4Me2SO(Im)] (NAMI; where Im is imidazole), a novel anti-neoplastic ruthenium(III) complex, with BSA, was studied in detail by various physico-chemical techniques. It is shown that NAMI, following chloride hydrolysis, binds bovine serum albumin tightly; spectrophotometric and atomic absorption data point out that up to five ruthenium ions are bound per albumin molecule when BSA is incubated for 24 h with an eightfold excess of NAMI. CD and electronic absorption results show that the various ruthenium centers bound to albumin exhibit well distinct spectroscopic features. The first ruthenium equivalent produces a characteristic positive CD band at 415 nm whereas the following NAMI equivalents produce less specific and less marked spectral effects. At high NAMI/BSA molar ratios a broad negative CD band develops at 590 nm. Evidence is provided that the bound ruthenium centers remain in the oxidation state +3. By analogy with the case of transferrins it is proposed that the BSA-bound ruthenium ions are ligated to surface histidines of the protein; results from chemical modification experiments with diethylpyrocarbonate seem to favor this view. Spectral patterns similar to those shown by NAMI are observed when BSA is reacted with two strictly related ruthenium(III) complexes Na[transRuCl4(Me2SO)2] and H(Im)[transRuCl4(Im)2] (ICR), implying a similar mechanism of interaction in all cases. It is suggested that the described NAMI-BSA adducts may form in vivo and may be relevant for the biological properties of this complex; alternatively NAMI/BSA adducts may be tested as specific carriers of the ruthenium complex to cancer cells. Implications of these findings for the mechanism of action of NAMI and of related ruthenium(III) complexes are discussed. [source] Circular dichroism spectroscopic study of non-covalent interactions of poly- L -glutamic acid with a porphyrin derivative in aqueous solutionsJOURNAL OF PEPTIDE SCIENCE, Issue 9 2005Palivec Abstract The interactions of poly- L -glutamic acid and a cationic porphyrin derivative in aqueous solutions were studied by the combination of vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectroscopies. It was found that non-covalent interactions between both agents influence the structure of the polymeric matrix and the guest porphyrins and vice versa, but the physico-chemical properties of the solutions, especially the pH and the relative permittivity of the solvent, play a key role in the structure of the polypeptide part of the formed complexes. It was shown that the interaction with porphyrins prevents the precipitation of poly- L -glutamic acid in aqueous solution at acidic pH. In special conditions, the porphyrins attached to the polypeptide probably possess face-to-face interaction as demonstrated by the enhancement of the characteristic ECD signal and the appearance of sidebands on its short and long wavelength sides. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source] Sodium 1, 4-dihydroxy-9, 10-anthraquinone- 2-sulphonate interacts with calf thymus DNA in a way that mimics anthracycline antibiotics: an electrochemical and spectroscopic studyJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 6 2010Partha Sarathi Guin Abstract The anthracycline drugs, adriamycin and daunorubicin, efficient in the treatment of various human cancers, form strong intercalation complexes with DNA. The therapeutic efficiency and toxic properties of the drugs are associated with electron transfer processes, which correlate well with the redox behaviour of the compounds. Sodium 1,4-dihydroxy 9,10-anthraquinone-2-sulphonate (sodium quinizarin-2-sulphonate, NaLH2) (Na-Qz-2S) is a molecule that resembles anthracycline drugs and has a simpler structure in comparison to these drugs. Two electrons in the course of chemical action reduce this molecule like the anthracyclines. Electrochemical methods were used to identify this process. UV-Vis and fluorescence spectroscopy were used to analyse binding of the compound to calf thymus DNA. The binding constant and site size were evaluated for Na-Qz-2S and the same compared to that of the anthracyclines. Such comparisons are essential in order to understand whether the simpler hydroxy-anthraquinones can be a substitute for anthracycline drugs in cancer chemotherapy. Copyright © 2009 John Wiley & Sons, Ltd. [source] Aromatic nitro substitution reaction between 4-nitro- N - n -butyl-1,8-naphthalimide and n -heptanethiol in water,methanol binary mixturesJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 7 2009Eduardo Rezende Triboni Abstract The second-order rate constants of thiolysis by n -heptanethiol on 4-nitro- N - n -butyl-1,8-naphthalimide (4NBN) are strongly affected by the water,methanol binary mixture composition reaching its maximum at around 50% mole fraction. In parallel solvent effects on 4NBN absorption molar extinction coefficient also shows a maximum at this composition region. From the spectroscopic study of reactant and product and the known H-bond capacity of the mixture a rationalization that involves specific solvent H-donor interaction with the nitro group is proposed to explain the kinetic data. Present findings also show a convenient methodology to obtain strongly fluorescent imides, valuable for peptide and analogs labeling as well as for thio-naphthalimide derivatives preparations. Copyright © 2008 John Wiley & Sons, Ltd. [source] Raman spectroscopy of synthetic, geological and biological vaterite: a Raman spectroscopic studyJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2010U. Wehrmeister Abstract Raman spectroscopy was used to study vaterite samples of biological, geological and synthetic origin. The Raman band positions and the full width at half-maximum (FWHM) of the lattice modes and the internal modes of the carbonate ion of all specimens show no significant differences between vaterites of different origin. With increasing Mg concentrations, synthetic vaterite samples show increasing FWHM in the region of the lattice modes and the three ,1 bands, whereas no change in luminescence was detected. In contrast, in situ measurements of vaterite areas in freshwater cultured pearls (FWCPs) by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) together with the Raman spectra obtained at the same points show that the luminescence intensity in biological samples is affected by the magnesium content. The Raman spectroscopic features of vaterite and parisite-(Ce) are compared, and their similarities suggest that the structure of vaterite contains at least three crystallographically independent carbonate groups and similar carbonate group layers. A band at 263 cm,1 is observed for the first time in this study, whereas it could be demonstrated that bands previously reported at 130 and 190 cm,1 do not belong to vaterite. Copyright © 2009 John Wiley & Sons, Ltd. [source] Raman spectroscopic study of the phosphate mineral churchite-(Y) YPO4·2H2OJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2010Ray L. Frost Abstract Raman spectroscopy has been used to study the rare-earth mineral churchite-(Y) of formula (Y,REE)(PO4) ·2H2O, where rare-earth element (REE) is a rare-earth element. The mineral contains yttrium and, depending on the locality, a range of rare-earth metals. The Raman spectra of two churchite-(Y) mineral samples from Jáchymov and Medv,dín in the Czech Republic were compared with the Raman spectra of churchite-(Y) downloaded from the RRUFF data base. The Raman spectra of churchite-(Y) are characterized by an intense sharp band at 975 cm,1 assigned to the ,1 (PO43,) symmetric stretching mode. A lower intensity band observed at around 1065 cm,1 is attributed to the ,3 (PO43,) antisymmetric stretching mode. The (PO43,) bending modes are observed at 497 cm,1 (,2) and 563 cm,1 (,4). Some small differences in the band positions between the four churchite-(Y) samples from four different localities were found. These differences may be ascribed to the different compositions of the churchite-(Y) minerals. Copyright © 2009 John Wiley & Sons, Ltd. [source] Raman spectroscopic study of the uranyl mineral pseudojohannite Cu6.5[(UO2)4O4(SO4)2]2(OH)5·25H2OJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2009Ray L. Frost Abstract Raman spectra of pseudojohannite were studied and related to the structure of the mineral. Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (SO4)2, units and of water molecules. The published formula of pseudojohannite is Cu6.5(UO2)8[O8](OH)5[(SO4)4]·25H2O. Raman bands at 805 and 810 cm,1 are assigned to (UO2)2+ stretching modes. The Raman bands at 1017 and 1100 cm,1 are assigned to the (SO4)2, symmetric and antisymmetric stretching vibrations. The three Raman bands at 423, 465 and 496 cm,1 are assigned to the (SO4)2,,2 bending modes. The bands at 210 and 279 cm,1 are assigned to the doubly degenerate ,2 bending vibration of the (UO2)2+ units. UO bond lengths in uranyl and OH···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd. [source] Raman spectroscopic study of the magnesium-carbonate minerals,artinite and dypingiteJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2009Ray L. Frost Abstract Magnesium minerals are important in the understanding of the concept of geosequestration. The two hydrated hydroxy magnesium-carbonate minerals artinite and dypingite were studied by Raman spectroscopy. Intense bands are observed at 1092 cm,1 for artinite and at 1120 cm,1 for dypingite, attributed ,1 symmetric stretching mode of CO32,. The ,3 antisymmetric stretching vibrations of CO32, are extremely weak and are observed at 1412 and 1465 cm,1 for artinite and at 1366, 1447 and 1524 cm,1 for dypingite. Very weak Raman bands at 790 cm,1 for artinite and 800 cm,1 for dypingite are assigned to the CO32,,2 out-of-plane bend. The Raman band at 700 cm,1 of artinite and at 725 and 760 cm,1 of dypingite are ascribed to CO32,,2 in-plane bending mode. The Raman spectrum of artinite in the OH stretching region is characterised by two sets of bands: (1) an intense band at 3593 cm,1 assigned to the MgOH stretching vibrations and (2) the broad profile of overlapping bands at 3030 and 3229 cm,1 attributed to water stretching vibrations. X-ray diffraction studies show that the minerals are disordered. This is reflected in the difficulty of obtaining Raman spectra of reasonable quality, and explains why the Raman spectra of these minerals have not been previously or sufficiently described. Copyright © 2008 John Wiley & Sons, Ltd. [source] OH-thermometry using laser polarization spectroscopy and laser-induced fluorescence spectroscopy in the OH A-X (1,0) bandJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2009J. Kiefer Abstract Laser-induced fluorescence (LIF) and polarization spectroscopy (PS) is used for OH-thermometry utilizing the off-diagonal A-X (1,0) band. Both techniques are used simultaneously in order to allow a comparison of the results. For deriving temperature information from the spectra, three methods are employed: (1) a contour fit method comparing experimental and calculated spectra, (2) spectral fitting of a single highly resolved spectral line and (3) a two-line intensity ratio approach. In general, both spectroscopic techniques gave similar results. The high-resolution approach (2) did not deliver reasonable results in our experiments. The most accurate but also most time consuming method was the contour fit (1). For future two-dimensional temperature measurements, the 2-line-method (3) was identified to be the method of choice. The present study contains, to the best of our knowledge, the first polarization spectroscopic study in the A-X (1,0) band of OH. Copyright © 2009 John Wiley & Sons, Ltd. [source] Raman spectroscopic study of the uranyl phosphate mineral dumontite Pb2 [(UO2)3O2(PO4)2]·5H2 OJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2009Ray L. Frost Abstract Raman spectra of dumontite were measured at 298 and 77 K. Observed bands were attributed to the stretching and bending vibrations of uranyl and phosphate units and OH stretching vibrations of water molecules. U,O bond lengths in uranyls and approximate O,H···O bond lengths were calculated. The values of the U,O bond lengths are in agreement with the data from the single crystal structure analysis of dumontite. Copyright © 2008 John Wiley & Sons, Ltd. [source] Raman spectroscopic study of the mineral guilleminite Ba(UO2)3(SeO3)2(OH)4·3H2OJOURNAL OF RAMAN SPECTROSCOPY, Issue 4 2009Ray L. Frost Abstract The Raman spectrum of the mineral guilleminite Ba[(UO2)3O2(SeO3)2](H2O)3 was studied and complemented by the infrared spectrum of this mineral. Both spectra were interpreted and compared with the spectra of marthozite, larisaite, haynesite and piretite, all of which should have the same phosphuranylite anion sheet topology. The presence of symmetrically distinct water molecules and hydrogen bonds was inferred from the spectra. This is in agreement with the crystal structural analysis of guilleminite. UO bond lengths in uranyl and OH···O hydrogen bond lengths were calculated from the Raman and/or infrared spectra of guilleminite. Copyright © 2008 John Wiley & Sons, Ltd. [source] Structural conformations and electronic interactions of the natural product, oroxylin: a vibrational spectroscopic studyJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2008Jose P. Abraham Abstract The oroxylin, 5,7-dihydroxy 6-methoxy flavone is a potent natural product extracted from ,Vitex peduncularis'. Density functional theory (DFT) at B3LYP/6-311G(d,p) level has been used to compute energies of different conformers of oroxylin to find out their stability, the optimized geometry of the most stable conformer and its vibrational spectrum. The conformer ORLN-1 with torsion angles 0, 180, 180 and 0 degrees, respectively, for H13O12C6C5, H14O10C4C5, H13O12C6C5 and H14O10C4C5 is found to be most stable. The optimized geometry reveals that the dihedral angle , between phenyl ring B and the chrome part of the molecule in , 19.21° is due to the repulsive force due to steric interaction between the ortho-hydrogen atom H29 of the B ring and H18 of the ring C (H29·H18 = 2.198 Å). A vibrational analysis based on the near-infrared Fourier transform(NIR-FT) Raman, Fourier transform-infrared (FT-IR) and the computed spectrum reveals that the methoxy group is influenced by the oxygen lone pair-aryl pz orbital by back donation. Hence the stretching and bending vibrational modes of the methoxy group possess the lowest wavenumber from the normal values of methyl group. The carbonyl stretching vibrations have been lowered due to conjugation and hydrogen bonding in the molecules. The intramolecular H-bonding and nonbonded intramolecular interactions shift the band position of O10H14 and O12H13 stretching modes, which is justified by DFT results. Copyright © 2008 John Wiley & Sons, Ltd. [source] Raman spectroscopic study of the uranyl selenite mineral marthozite Cu[(UO2)3(SeO3)2O2]·8H2OJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2008Ray L. Frost Abstract The mineral marthozite, a uranyl selenite, has been characterised by Raman spectroscopy at 298 K. The bands at 812 and 797 cm,1 were assigned to the symmetric stretching modes of the (UO2)2+ and (SeO3)2, units, respectively. These values gave the calculated UO bond lengths in uranyl of 1.799 and/or 1.814 Å. Average UO bond length in uranyl is 1.795 Å, inferred from the X-ray single crystal structure analysis of marthozite by Cooper and Hawthorne. The broad band at 869 cm,1 was assigned to the ,3 antisymmetric stretching mode of the (UO2)2+ (calculated UO bond length 1.808 Å). The band at 739 cm,1 was attributed to the ,3 antisymmetric stretching vibration of the (SeO3)2, units. The ,4 and the ,2 vibrational modes of the (SeO3)2, units were observed at 424 and 473 cm,1. Bands observed at 257, and 199 and 139 cm,1 were assigned to OUO bending vibrations and lattice vibrations, respectively. OH···O hydrogen bond lengths were inferred using Libowiztky's empirical relation. The infrared spectrum of marthozite was studied for complementation. Copyright © 2008 John Wiley & Sons, Ltd. 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