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In the present article, the molecular structure of S-methyl thiobutanoate, CH 3 CH 2 CH 2 C(O)SCH 3 was determined by ab initio (MP2) and DFT calculations using different basis sets. The infrared and Raman spectra for the liquid phase were also recorded and the bands observed were assigned to the vibrational normal modes. The experimental and calculations confirm the presence of two most stable conformers, one with pseudo anti – syn conformation and another with gauche – syn conformation. The study was completed using natural bond orbital (NBO) and AIM analysis. The molecular properties like dipole moment, molecular electrostatic potential surface (MEP) and HOMO–LUMO molecular orbitals were calculated to get a better insight of the properties of the title molecule. Global and local reactivity descriptors were computed in order to predict reactivity and reactive sites on the molecule for nucleophilic, electrophilic and radical attacks. [ABSTRACT FROM AUTHOR]

The mineral tilleyite-Y, a carbonate-silicate of calcium, has been studied by scanning electron microscopy with chemical analysis using energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the tilleyite structure. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water in different molecular environments in the structure of tilleyite. Vibrational spectroscopy offers new information on the mineral tilleyite. [ABSTRACT FROM AUTHOR]

The mineral brianyoungite, a carbonate–sulphate of zinc, has been studied by scanning electron microscopy (SEM) with chemical analysis using energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the brianyoungite structure. Intense Raman band at 1056 cm −1 with shoulder band at 1038 cm −1 is assigned to the CO 3 2 − ν 1 symmetric stretching mode. Two intense Raman bands at 973 and 984 cm −1 are assigned to the symmetric stretching modes of the SO 4 2 − anion. The observation of two bands supports the concept of the non-equivalence of sulphate units in the brianyoungite structure. Raman bands at 704 and 736 cm −1 are assigned to the CO 3 2 − ν 4 bending modes and Raman bands at 507, 528, 609 and 638 cm −1 are assigned to the CO 3 2 − ν 2 bending modes. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water and hydroxyl units in different molecular environments in the structure of brianyoungite. Vibrational spectroscopy enhances our knowledge of the molecular structure of brianyoungite. [ABSTRACT FROM AUTHOR]

We have studied the carbonate mineral kamphaugite-(Y)(CaY(CO 3 ) 2 (OH)·H 2 O), a mineral which contains yttrium and specific rare earth elements. Chemical analysis shows the presence of Ca, Y and C. Back scattering SEM appears to indicate a single pure phase. The vibrational spectroscopy of kamphaugite-(Y) was obtained using a combination of Raman and infrared spectroscopy. Two distinct Raman bands observed at 1078 and 1088 cm −1 provide evidence for the non-equivalence of the carbonate anion in the kamphaugite-(Y) structure. Such a concept is supported by the number of bands assigned to the carbonate antisymmetric stretching mode. Multiple bands in the ν 4 region offers further support for the non-equivalence of carbonate anions in the structure. Vibrational spectroscopy enables aspects of the structure of the mineral kamphaugite-(Y) to be assessed. [ABSTRACT FROM AUTHOR]

We have studied the mineral poldervaartite CaCa[SiO 3 (OH)(OH)] which forms a series with its manganese analogue olmiite CaMn[SiO 3 (OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is reasonably pure and contains only calcium and manganese with low amounts of Al and F. Thermogravimetric analysis proves the mineral decomposes at 485 °C with a mass loss of 7.6% compared with the theoretical mass loss of 7.7%. A strong Raman band at 852 cm −1 is assigned to the SiO stretching vibration of the SiO 3 (OH) units. Two Raman bands at 914 and 953 cm −1 are attributed to the antisymmetric vibrations. Intense prominent peaks observed at 3487, 3502, 3509, 3521 and 3547 cm −1 are assigned to the OH stretching vibration of the SiO 3 (OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of poldervaartite. [ABSTRACT FROM AUTHOR]

The mineral tengerite-(Y) has been studied by vibrational spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the tengerite-(Y) structure. Intense sharp bands at 464, 479 and 508 cm −1 are assigned to YO stretching modes. Raman bands at 765 and 775 cm −1 are assigned to the CO 3 2 − ν 4 bending modes and Raman bands at 589, 611, 674 and 689 cm −1 are assigned to the CO 3 2 − ν 2 bending modes. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water in different molecular environments in the structure of tengerite-(Y). [ABSTRACT FROM AUTHOR]

In this work we have studied the mineral dawsonite by using a combination of scanning electron microscopy with EDS and vibrational spectroscopy. Single crystals show an acicular habitus forming aggregates with a rosette shape. The chemical analysis shows a phase composed of C, Al, and Na. Two distinct Raman bands at 1091 and 1068 cm −1 are assigned to the CO 3 2 − ν 1 symmetric stretching mode. Multiple bands are observed in both the Raman and infrared spectra in the antisymmetric stretching and bending regions showing that the symmetry of the carbonate anion is reduced and in all probability the carbonate anions are not equivalent in the dawsonite structure. Multiple OH deformation vibrations centred upon 950 cm −1 in both the Raman and infrared spectra show that the OH units in the dawsonite structure are non-equivalent. Raman bands observed at 3250, 3283 and 3295 cm −1 are assigned to OH stretching vibrations. The position of these bands indicates strong hydrogen bonding of the OH units in the dawsonite structure. The formation of the mineral dawsonite has the potential to offer a mechanism for the geosequestration of greenhouse gases. [ABSTRACT FROM AUTHOR]

A new organic–inorganic hybrid material, 1,4-bis(3-ammoniumpropyl) piperazinium pentachloridocuprate(II) chloride tetrahydrate [(C 10 H 28 N 4 )CuCl 5 Cl⋅4H 2 O], has been synthesized and characterized by X-ray diffraction, UV–visible absorption, Infrared and Raman spectroscopy. The compound crystallizes in the orthorhombic system and Pnma space group with a = 8.18 (3) Å, b = 10.96 (5) Å, c = 21.26 (9) Å, V = 2254.3 (15) Å 3 . In this structure, the Cu 2+ ion, surrounded by five chlorides, adopts the square pyramidal coordination geometry. The structure of this compound consists of tetraprotonated 1,4-bis(3-ammoniumpropyl) piperazinium cations and the anionic sublattice is built up of isolated, square pyramid [CuCl 5 ] 3 − units, chloride ion Cl − and water molecules connected with each other by hydrogen bonds. Organic and inorganic entities are interconnected by means of hydrogen bonding contacts [N H⋯O(Cl), O(W) H⋯Cl and O(W) H⋯O]. Furthermore, the room temperature IR and Raman spectra of the title compound were recorded and analyzed on the basis of literature data. The optical study was also investigated by UV–Vis absorption. In fact, the organic–inorganic hybrid crystal thin film can be easily prepared by spin-coating method from the ethanol solution of the (C 10 H 28 N 4 )CuCl 5 Cl⋅4H 2 O hybrid compound and it showed absorptions characteristics of Cu Cl based layered compounds centered at 275 and 374 nm. [ABSTRACT FROM AUTHOR]

Nine hybrid silicas bearing the organic substituent groups methyl, octyl, octadecyl, vinyl, phenyl, mercaptopropyl, isocyanatopropyl, chloropropyl and glycidoxypropyl were synthesized by an acid-catalyzed, hydrolytic sol-gel process. The resulting solid materials were characterized by their absorbance and attenuated total reflection (ATR) IR and Raman spectra. The latter technique proved to be particularly useful in the identification of the organic moieties in the hybrid silicas. The effect of the presence of the organic groups on the silica networks was also investigated - there were increases observed in both the SiOSi bond angles and bond lengths. Moreover, deconvolution of the IR-active antisymmetric SiOSi stretching bands permitted detection of the four- and six-membered siloxane rings present in the silicas. There proved to be a greater number of four-membered rings on the surfaces of the particles. Both IR and Raman spectroscopy proved to be invaluable in the characterization of these hybrid materials. [ABSTRACT FROM AUTHOR]

Highlights: [•] The morphology of the BMST crystal was depicted using WinXMorph program. [•] FT-IR, FT-Raman and 1H NMR assignments confirmed the functional groups of BMST. [•] Bond length alternation value was found to be 0.086Å. [•] Band gap energy and refractive index were found to be 2.96eV and 2.41 respectively. [•] Kurtz powder test confirmed that SHG intensity increases with increase in particle size. [ABSTRACT FROM AUTHOR]

Highlights: [•] The conformational behavior was studied by ab initio and DFT calculations. [•] FTIR and Raman investigation of 2,2,2-trichloroethylacetate were carried out. [•] The fundamental vibrational modes were assigned. [•] NBO and AIM analysis were performed in order to investigate the conformational preference. [Copyright &y& Elsevier]

Highlights: [•] Specimen Trichocline reptans. [•] Infrared and Raman spectra. [•] X-ray diffraction methods. [Copyright &y& Elsevier]

Highlights: [•] The molecular structure of the compound has been determined by X-ray diffraction. [•] The substance crystallizes in the monoclinic P21/c space group with Z =8 molecules per unit cell. [•] The conformers are arranged in the lattice as center-symmetric N H⋯O(sulf) bonded dimers. [•] For NBO analysis, the hyperconjugative interactions are favored in conformer 2 than conformer 1. [•] Infrared and Raman spectra showed bands assignable to 34 of the 36 vibrational normal modes. [ABSTRACT FROM AUTHOR]

Abstract: Raman and infrared spectra of rondorfite Ca8Mg(SiO4)4Cl2, a calcium chlorosilica mineral containing magnesium in tetrahedral position, has been studied in terms of spectra-structure relations. Raman spectra have been measured at different excited laser lines: 780nm, 532nm, 488nm and 457nm. This mineral is characterized by a single sharp intense Raman band at 863cm−1 assigned to the ν 1 [SiO4]4− (A g) symmetric stretching mode in the magnesiosilicate pentamer. Due to symmetry restriction the other Raman bands have a small intensity. Two Raman bands observed at 564cm−1 and 526cm−1 are associated simultaneously with ν 4 [MgO4]6− and ν 4 [SiO4]4− symmetric and antisymmetric modes where magnesium occurs in the tetrahedral configuration. The weak bands at 422cm−1 and 386cm−1 are associated with the ν 2 bending mode of CaO6 in octahedral configuration, respectively. Moreover the infrared spectrum shows very weak bands associated with the hydroxyl group and/or water molecule. Additionally, the strong fluorescence phenomenon was observed and related to the presence of chlorine atoms, magnesium Mg2+ ions in atypical configuration or point defects. [Copyright &y& Elsevier]

Abstract: Infrared emission and infrared spectroscopy has been used to study a series of selected natural smithsonites from different origins. An intense broad infrared band at 1440cm−1 is assigned to the CO3 2− antisymmetric stretching vibration. An additional band is resolved at 1335cm−1. An intense sharp Raman band at 1092cm−1 is assigned to the CO3 2− symmetric stretching vibration. Infrared emission spectra show a broad antisymmetric band at 1442cm−1 shifting to lower wavenumbers with thermal treatment. A band observed at 870cm−1 with a band of lesser intensity at 842cm−1 shifts to higher wavenumbers upon thermal treatment and is observed at 865cm−1 at 400°C and is assigned to the CO3 2− mode. No bending modes are observed in the Raman spectra for smithsonite. The band at 746cm−1 shifts to 743cm−1 at 400°C and is attributed to the CO3 2− in phase bending modes. Two infrared bands at 744 and around 729cm−1 are assigned to the in phase bending mode. Multiple bands may be attributed to the structural distortion ZnO6 octahedron. This structural distortion is brought about by the substitution of Zn by some other cation. A number of bands at 2499, 2597, 2858, 2954 and 2991cm−1 in both the IE and infrared spectra are attributed to combination bands. [Copyright &y& Elsevier]

Abstract: Raman spectra at 298 and 77K and infrared spectra of the uranyl sulfate mineral zippeite from Jáchymov (Joachimsthal), Czech Republic, K0.6(H3O)0.4[(UO2)6(SO4)3(OH)7]·8H2O, were studied. Observed bands were tentatively attributed to the (UO2)2+ and (SO4)2− stretching and bending vibrations, the OH stretching vibrations of water molecules, hydroxyls and oxonium ions, and H2O, oxonium, and δ U–OH bending vibrations. Empirical relations were used for the calculation of U–O bond lengths in uranyl R (Å)= f(ν 3 or ν 1(UO2)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. [Copyright &y& Elsevier]

Abstract: Minerals in the rosasite group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by a combination of infrared and Raman spectroscopy. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at ∼3401 and 3311cm−1. Two intense bands observed at ∼1096 and 1046cm−1 are assigned to ν 1(CO3)2− symmetric stretching vibration and the δ OH deformation mode. Multiple bands are found in the 800–900 and 650–750cm−1 regions attributed to the ν 2 and ν 4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C 2v or C s. A band at ∼560cm−1 is assigned to a CuO stretching mode. [Copyright &y& Elsevier]

Abstract: The optical spectrum of Mn2+ in octahedral coordination for sursassite is characterized by well resolved bands at 580, 515, 470, 390, 340, and 295nm (17240, 19420, 21280, 25640, 29410 and 33900cm−1). Crystal field parameters evaluated from the observed bands are Dq=690, B =680 and C =2800cm−1. A broad band centred around 13000cm−1 attributed to Fe(III) ion is an impurity in sursassite confirmed from EDX analysis. Vibrational spectra have been investigated both by IR and Raman spectroscopy. The correlation between vibrational modes and the structural properties of the manganese silicate, sursassite, is made and compared with other silicates. Two vibrational modes of CO3 2− observed; the antisymmetric stretching mode (ν 3) at 1420cm−1 (IR active) and the out-of-plane bending mode (ν 2) (IR and Raman active) at ∼875cm−1. This confirms the Mn rich phases in sursassite as observed from SEM probably an Mn carbonate-rhodochrosite. [Copyright &y& Elsevier]

Abstract: Raman spectroscopy has been used to study the molecular structure of a series of selected uranyl silicate minerals including weeksite K2[(UO2)2(Si5O13)]·H2O, soddyite [(UO2)2SiO4·2H2O] and haiweeite Ca[(UO2)2(Si5O12(OH)2](H2O)3 with UO2 2+/SiO2 molar ratio 2:1 or 2:5. Raman spectra clearly show well resolved bands in the 750–800cm−1 region and in the 950–1000cm−1 region assigned to the ν1 modes of the (UO2)2+ units and to the (SiO4)4− tetrahedra. Soddyite is characterized by Raman bands at 828.0, 808.6 and 801.8cm−1, 909.6 and 898.0cm−1, and 268.2, 257.8 and 246.9cm−1, attributed to the ν1, ν3, and ν2 (δ) (UO2)2+, respectively. Coincidences of the ν1 (UO2)2+ and the ν1 (SiO4)4− is expected. Bands at 1082.2, 1071.2, 1036.3, 995.1 and 966.3cm−1 are attributed to the ν3 (SiO4)4−. Sets of Raman bands in the 200–300cm−1 region are assigned to ν2 (δ) (UO2)2+ and UO ligand vibrations. Multiple bands indicate the non-equivalence of the UO bonds and the lifting of the degeneracy of ν2 (δ) (UO2)2+ vibrations. The (SiO4)4− tetrahedral are characterized by bands in the 470–550cm−1 and in the 390–420cm−1 region. These bands are attributed to the ν4 and ν2 (SiO4)4− bending modes. The minerals show characteristic OH stretching bands in the 2900–3500 and 3600–3700cm−1. [Copyright &y& Elsevier]

Abstract: Raman spectroscopy at 298 and 77K has been used to study the secondary uranyl mineral johannite of formula (Cu(UO2)2(SO4)2(OH)2·8H2O). Four Raman bands are observed at 3593, 3523, 3387 and 3234cm−1 and four infrared bands at 3589, 3518, 3389 and 3205cm−1. The first two bands are assigned to OH− units (hydroxyls) and the second two bands to water units. Estimations of the hydrogen bond distances for these four bands are 3.35, 2.92, 2.79 and 2.70Å. A sharp intense band at 1042cm−1 is attributed to the (SO4)2− symmetric stretching vibration and the three Raman bands at 1147, 1100 and 1090cm−1 to the (SO4)2− anti-symmetric stretching vibrations. The ν 2 bending modes were at 469, 425 and 388cm−1 at 77K confirming the reduction in symmetry of the (SO4)2− units. At 77K two bands at 811 and 786cm−1 are attributed to the ν 1 symmetric stretching modes of the (UO2)2+ units suggesting the non-equivalence of the UO bonds in the (UO2)2+ units. The band at 786cm−1, however, may be related to water molecules libration modes. In the 77K Raman spectrum, bands are observed at 306, 282, 231 and 210cm−1 with other low intensity bands found at 191, 170 and 149cm−1. The two bands at 282 and 210cm−1 are attributed to the doubly degenerate ν 2 bending vibration of the (UO2)2+ units. Raman spectroscopy can contribute significant knowledge in the study of uranyl minerals because of better band separation with significantly narrower bands, avoiding the complex spectral profiles as observed with infrared spectroscopy. [Copyright &y& Elsevier]