Raman Study Of Single Crystals Research Articles

Mcconnellite, CuCrO2 and ellinaite, CaCr2O4, from varicoloured spurrite marble of the Daba-Siwaqa area, Hatrurim Complex, Jordan

Abstract A common attribute of two rare natural chromium-bearing oxides: mcconnellite, CuCrO2, discovered more than 40 years ago in Guyana, and a new mineral ellinaite, CaCr2O4, described from two localities (Brazil and Israel) recently, is that these minerals are poorly studied due to their rarity and small size. Mcconnellite and ellinaite in the present study were found in varicoloured marbles of the pyrometamorphic Hatrurim Complex in the Tulul Al Hammam area, Daba-Siwaqa, Jordan. Structural data obtained for ellinaite (Pnma, a = 9.0875(2), b = 2.9698(1), c = 10.6270(3) Å and V = 286.80(2) Å3), with an empirical formula (Сa1.00Sr0.01)Σ1.01(Cr3+1.79Al0.07Ca0.04Fe3+0.04 Ti4+0.03Mg0.03)Σ2.00O4, is similar to the structural data of synthetic analogue β-CaCr2O4 but differs significantly from the data obtained for ellinaite from Brazil and Israel despite the fact that all the natural phases have a similar composition. Single-crystal X-ray diffraction data for mcconnellite from Jordan (R $\bar{3}$ m, a = b = 2.9756(1) and c = 17.124(1) Å) with composition (Cu0.98Ca0.03Sr0.01)Σ1.02(Cr3+0.90Al0.05 Fe3+0.03)Σ0.98O2, is the first determination of a natural Cu-delafossite-type structure. This paper also presents the results of a single-crystal Raman study for mcconnellite and ellinaite, which indicates that the spectral features of these minerals is dependent on crystal orientation.

Detecting a quasi-stable imine species on the reaction pathway of SHV-1 β-lactamase and 6β-(hydroxymethyl)penicillanic acid sulfone.

For the class A β-lactamase SHV-1, the kinetic and mechanistic properties of the clinically used inhibitor sulbactam are compared with the sulbactam analog substituted in its 6β position by a CH2OH group (6β-(hydroxymethyl)penicillanic acid). The 6β substitution improves both in vitro and microbiological inhibitory properties of sulbactam. Base hydrolysis of both compounds was studied by Raman and NMR spectroscopies and showed that lactam ring opening is followed by fragmentation of the dioxothiazolidine ring leading to formation of the iminium ion within 3 min. The iminium ion slowly loses a proton and converts to cis-enamine (which is a β-aminoacrylate) in 1 h for sulbactam and in 4 h for 6β-(hydroxymethyl) sulbactam. Rapid mix–rapid freeze Raman spectroscopy was used to follow the reactions between the two sulfones and SHV-1. Within 23 ms, a 10-fold excess of sulbactam was entirely hydrolyzed to give a cis-enamine product. In contrast, the 6β-(hydroxymethyl) sulbactam formed longer-lived acyl–enzyme intermediates that are a mixture of imine and enamines. Single crystal Raman studies, soaking in and washing out unreacted substrates, revealed stable populations of imine and trans-enamine acyl enzymes. The corresponding X-ray crystallographic data are consonant with the Raman data and also reveal the role played by the 6β-hydroxymethyl group in retarding hydrolysis of the acyl enzymes. The 6β-hydroxymethyl group sterically hinders approach of the water molecule as well as restraining the side chain of E166 that facilitates hydrolysis.

Single crystal Raman studies of six-fold gibbsite twins

Single crystal Raman studies of six-fold gibbsite twins

Lattice vibration spectra Part XCI. Single-crystal Raman and single-crystal neutron diffraction studies on partially deuterated Ca(IO3)2·6H2O; assignment of hydrogen bonds

The crystal structure of Ca(IO3)2·6H2O (Fdd2, Z = 8, a = 1485.9(1) pm, b = 2301.8(2) pm, and c = 639.44(5) pm, RW = 4.7%) has been refined by single-crystal neutron diffraction studies on the basis of 1150 reflections using the Becker and Coppens formalism for refinement of the extinction parameters. The X-ray structure reported in the literature has been confirmed and the positions of the six crystallographically different hydrogen atoms have been established for the first time. The H⋯O distances of the hydrogen bonds formed are 167.8, 177.8, 180.2, 191.8, 194.8, and 198.0 pm, which correspond to the six uncoupled OD stretching modes (2307, 2378, 2409, 2488, 2516, and 2526 cm−1, 90 K) in the infrared and Raman spectra of isotopically dilute samples. For assignment of the observed bands to the hydrogen positions of the structure we performed single-crystal Raman studies on partially deuterated samples, as proposed in 1984. The limits of this procedure and those of other methods for assigning water bands and the relationship of the strengths of the hydrogen bonds with spectroscopic and structural data, including bond valences and IO⋯H bond angles, are discussed.

Raman study of crystals

In this work we present a polarized Raman study of single crystals for several values of the concentration made using different scattering geometries. The Raman spectra, composed of broad bands, have been fitted in accordance with a symmetry analysis which allowed us to assign the vibrational modes, and determine their frequencies and damping constants. The results are compatible with an average hexagonal symmetry for the solid solutions with x in the range . In each of the spectra we found two bands at about 590 and , probably associated with the existence of structures in the solid solutions.

Lattice Vibration Spectra. LXXV. IR Single Crystal Reflection Spectra of Sr(ClO3)2

Abstract Polarized infrared reflection spectra of Sr(ClO3)2 single-crystal plates are recorded and analysed for the frequencies of the transversal and longitudinal optical zone-centre phonon modes and other oscillator parameters by Kramers-Kronig analyses and both the classical 3 parameter (dielectric sum-function) and the 4 parameter (factorized form) oscillator-fit methods. The frequencies computed are compared with the results of previous single-crystal Raman studies. Because of the great distortion of the ClO3 - ions (site symmetry C1, no intraionic coupling of the CIO vibrations to symmetric ( ν 1) and asymmetric (ν3) stretching modes occurs. The TO/LO splittings of respective CIO unit-cell group modes rank like the vector elements of the corresponding CIO bonds with respect to the crystal axe

Laser Raman study of the low-temperature phase transformation in [N(CH3)4]2CuCl4 single crystals

Abstract The results of a detailed temperature-dependent Raman study of single crystals of [N(CH 3 ) 4 ] 2 CuCl 4 are reported in different spectral regions. The observed splittings of the symmetric stretching modes of the N(CH 3 ) + 4 ion below 250 K and the CuCl 2− 4 ion below 50 K into doublets have been explained as being due to the presence of ions on two energetically inequivalent positions within the lattice. From a temperature dependence of the half-widths, frequency separation, relative intensities of the two components of the CN stretch and other thermosensitive spectral changes, we have discovered a new first order type phase transition in this system at ∼50 K due to ordering of ions from one configuration to another. The reordering in phase IV up to 50 K takes place via continuous movement of cations from the disordered to ordered configuration, but below 50 K the ions freeze in the two inequivalent configurations. The dynamics of ordering of the ions at different temperatures is discussed in this communication.

Single crystal Raman studies of the H 2O librational modes of isomorphic MX 2·H 2O (M = Ba, Sr; X = Br, I)

The librational modes of the water molecules in the isomorphic MX 2·Y 2O (M=Sr, Ba; X=Br, I; Y=H, D) are assigned to the wagging (R γ), twisting (Rt), and rocking vibrations (Rr) by means of single crystal Raman technique. The order of the librations in R γ > Rt > Rr in energy and Rt > Rr in intesity (R γ not observable), as predicted for tetrahedrally coordinated water molecules in solids. The data obtained are discussed with respect to (i) the strength of the hydrogen bonds, (ii) repulsive effects of the lattice (owing to the different volume increments of the H 2O molecules), and (iii) metal oxygen interactions (shown by the different enthalpies of hydration). The H 2O twisting vibrations are only little affected by the hydrogen bonds present (opposite to the wagging and rocking modes), but very sensitive to both repulsive effects and metal oxygen interaction.

Laser Raman study of single crystals of deuterated cadmium fluorosilicate

A laser Raman study of oriented single crystals of CdSiF 6:6D 2O at room temperature as well as at 10 K in all the six polarization geometries has been made. Also a detailed temperature dependent Raman study from room temperature to 10 K in ( yy) polarization in the region of internal vibrations and lattice modes has been made. Abrupt changes have been observed in frequency shift, line-width and intensity of some of the bands at about 235 K. Some doubly degenerate modes show splitting at the same temperature. From these observations a phase change at about 235 K is inferred for this salt. It has been suggested that when the system is cooled, the lattice contracts and the water molecules lose their reorientational freedom to some extent which might result in the distortion of the [Cd(OD 2) 6] 2+ octahedra triggering a phase transition.

Vibrational spectra of bis(halomercurio)methanes CH 2(HgX) 2 (X  Cl, Br and I) in poly- and monocrystalline states

Vibrational spectra of polycrystalline bis(chloromercurio)methane CH 2(HgCl) 2 (space group Pnma, Z = 4), and of the deuterated analogue, as representatives of the bis(halomercurio)methanes, are preliminarily assigned. Low-temperature Raman and IR spectra of CH 2(HgCl) 2 reveal correlation splittings between g and u species, and partly within the sets of g and u modes, as predicted by unit-cell group analysis. Single-crystal Raman studies not only confirm the suggested assignments but are also the only method to unequivocally assign some bands. The limitations of the applicability of unit-cell group analysis in the present case are discussed.

Infrared and single crystal Raman studies of alkaline earth chlorate, bromate and iodate monohydrates and of halate ions matrix isolated in Ba(ClO 3) 2·H 2Otype host lattices

The i.r. and Raman spectra including Raman single crystal measurements of the isostructural Ba(ClO 3) 2·H 2O, Ba(BrO 3) 2·H 2O, Sr(BrO 3) 2·H 2O, and Sr(IO 3) 2·H 2O and of Ba(ClO 3) 2·H 2O-Ba(BrO 3) 2·H 2O solid solutions are presented in the water band and the XO stretching mode region at 90 and 295 K. Assignment of the XO stretching modes to the intramolecular vibrations v 1 and v 3 of the halate ions and the species of the unit cell group C 2h is performed and discussed in terms of the relative intensity of the i.r. and Raman bands, the frequency shifting among the halate monohydrates, the single crystal Raman spectra and the spectra of matrix isolated ClO − 3 and BrO − 3 ions. The effective XO stretching force constants are in the order ClO − 3 > lO − 3 > BrO − 3. The order of v 1 and v 3 is v 1 < v 3 for ClO − 3 and v 1 > v 3 for BrO − 3 and IO − 3·. 33Cl/ 37Cl isotopic splitting of the ClO stretching modes, as discussed formerly, can be excluded. The spectra of matrix isolated ClO 3 − 3 and BrO − 3 ions (site symmetry C 1) show three XO stretching bands (one v 1 and two v 3). The frequency shifting of the OH stretching modes resembles that of other isostructural solid hydrates with weak hydrogen bonds. It can be correlated to the repulsion potential of the lattice and the metal—water interaction.

Is cerussite an aragonite? Longitudinal optical–transverse optical splitting in the single-crystal Raman spectra

Single-crystal Raman studies on cerussite, PbCO3, show longitudinal optical-transverse optical splitting effects and are incompatible with this material having the aragonite lattice; a Pna21, C2v9 structure is indicated.

Single crystal Raman studies on magnesium sulphite trihydrate, MgSO3·3H2O and MgSO3·3(H, D)2O

AbstractThe Raman and infrared spectra of MgSO3·3H2O and of deuteriated and isotopically dilute samples of this hydrate were recorded from 100 to 4000 cm−1 at 90–300 K and analysed with regard to the bonding structure of the water of crystallization, the space group of this compound, i.e. P212121, Pnma or Pn21a, and assignment and coupling (with the H2O and D2O librations) of the internal modes of the sulphite ions. The orientational behaviour of single crystal Raman studies on isotopically dilute samples are firstly used for assigning the uncoupled OH (OD) stretching modes to the H positions in the lattice. From the three types of water of crystallization (in the case of space group P212121 or Pn21a), the orientationally disordered H2O1 and H2O11 are involved in very strong hydrogen bonds, uncoupled OH (OD) modes 3027 (2282) and 2930 (2240) cm−1, caused by the strong hydrogen bond acceptor strength of the sulphite ions. Both water molecules are extremely distorted with OH (OD) mode splittings up to 393 (218) cm−1, the largest known so far. H2O111 forms weak bifurcated hydrogen bonds. Both the stretching and bending vibrations of the sulphite ions coincide with rotational modes of the water molecules.

Structural investigation of indium halide compounds: Single crystal Raman study of monohydrated potassium hexachloroindate

The Raman spectrum of K 3InCl 6, H 2O single crystal is assigned on the basis of the crystal structure knowledge. The main feature is the splitting of the ν 1 vibrational band into two components, that are assigned in relation to the indium site occupation ratio. In Raman spectroscopy, the superposition of the internal mode frequency range (characteristic of different anionic species), does not contribute to any improvement of the ionic isomerisation found by X-ray investigation.

Single-crystal raman study of dirhenium decacarbonyl

A single-crystal Raman study of Re 2(CO) 10 is reported from which 20 of the 21 Raman-active modes of this D 4 d molecule have been assigned. All six lattice modes were identified below 70 cm -1. In respect of the long-disputed assignment of v (Re--Re), for which two possibilities exist (107 and 129 dm -1), the balance of the new evidence is in favour of the lower band. Comparisons are drawn with assignments for Mn 2(CO) 10 and Re(CO) 5X, (X = halogen), respectively and anomalies noted.

Very strong hydrogen bonding: single crystal raman studies of potassium hydrogen oxalate and sodium hydrogen oxalate monohydrate

Single crystal Raman studies of potassium hydrogen oxalate and sodium hydrogen oxalate monohydrate are reported for the first time. Some modifications are suggested to the assignments made using powdered samples.

Dynamic sulfate disorder in potassium alum. A single crystal raman study

Single crystal Raman spectra of the ν 1 sulfate vibration of potassium aluminium alum are discussed in terms of a disordered structure. The temperature dependence of intensities suggests occupation of two surfate sites which differ by 2009 J mol −1 in energy.

ChemInform Abstract: ASPECTS OF THE STRUCTURE AND BONDING IN PRUSSIAN BLUES. SINGLE‐CRYSTAL RAMAN STUDY OF TRIMANGANESE HEXACYANOCOBALTATE HYDRATE (MN3(CO(CN)6).XH2O) AND TRICADMIUM BIS(HEXACYANOCOBALTATE) HYDRATE (CD3(CO(CN)6)2.XH2O)

Chemischer InformationsdienstVolume 7, Issue 16 Organoelement Compounds ChemInform Abstract: ASPECTS OF THE STRUCTURE AND BONDING IN PRUSSIAN BLUES. SINGLE-CRYSTAL RAMAN STUDY OF TRIMANGANESE HEXACYANOCOBALTATE HYDRATE (MN3(CO(CN)6).XH2O) AND TRICADMIUM BIS(HEXACYANOCOBALTATE) HYDRATE (CD3(CO(CN)6)2.XH2O) BASIL I. SWANSON, BASIL I. SWANSONSearch for more papers by this author BASIL I. SWANSON, BASIL I. SWANSONSearch for more papers by this author First published: April 20, 1976 https://doi.org/10.1002/chin.197616328AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume7, Issue16April 20, 1976 RelatedInformation

Aspects of the structure and bonding in Prussian Blues. Single-crystal Raman study of trimanganese hexacyanocobaltate hydrate (Mn3[Co(CN)6].xH2O) and tricadmium bis(hexacyanocobaltate) hydrate (Cd3[Co(CN)6]2.xH2O)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAspects of the structure and bonding in Prussian Blues. Single-crystal Raman study of trimanganese hexacyanocobaltate hydrate (Mn3[Co(CN)6].xH2O) and tricadmium bis(hexacyanocobaltate) hydrate (Cd3[Co(CN)6]2.xH2O)Basil I. SwansonCite this: Inorg. Chem. 1976, 15, 2, 253–259Publication Date (Print):February 1, 1976Publication History Published online1 May 2002Published inissue 1 February 1976https://doi.org/10.1021/ic50156a002RIGHTS & PERMISSIONSArticle Views255Altmetric-Citations35LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (939 KB) Get e-Alerts Get e-Alerts

Solid state studies. Part VII. A single-crystal Raman study of the vibration of the Cr(CO)3 unit in hexa- and penta-methylbenzenetricarbonylchromium

Single-crystal Raman studies of the isomorphous title compounds have shown that, whilst a vibrational factor-group method offers the simplest explanation of the 2000 cm–1 region, some features remain unexplained by it.