Vibrational spectra of barium oxalate hemihydrate

The infrared and Raman spectra of barium oxalate hemihydrate, BaC₂O₄ · 0.5H₂O, were recorded and discussed on the basis of their structural peculiarities and in comparison with the spectra of the previously investigated calcium and strontium oxalates.     

The shape and extended fine structure of the manganese K x-ray absorption discontinuity in some divalent compounds

We report in the present paper the shape and extended fine structure of the manganese K absorption discontinuity in four octahedral divalent compounds, viz. MnCl₂·4H₂O, MnSO₄·H₂O, MnC₂O₄·2H₂O and α-MnS. Molecular orbital theory is used to interpret the various features of the main absorption discontinuity. The extended X-ray absorption fine structure (EXAFS) is interpreted with the help of the graphical method given by Lytle et al.     

Raman and IR studies of TaWO5.5, ASbWO6 (A = K,Rb, Cs,Tl), and ASbWO6·H2O (A = H,NH4, Li,Na) pyrochlore oxides

Raman and infrared (IR) spectra of defect pyrochlores TaWO_5.5, NH₄SbWO₆·H₂O, HSbWO₆·H₂O, LiSbWO₆·H₂O, NaSbWO₆·H₂O, KSbWO₆, RbSbWO₆, CsSbWO₆, and TlSbWO₆ were measured. The obtained spectra are discussed using the factor group approach for the cubic Fd‐3m space group, and assignment of bands to respective motions of atoms is proposed. Our results show that the phonon properties of the pyrochlores are strongly affected by disorder, and therefore Raman and IR spectroscopies are very useful tools in studying disorder in this family of compounds. In particular, our studies have shown that in these ionic conductors disorder at sites occupied by NH , H⁺, or alkali‐metal ions decreases with increasing size and mass of these ions. Copyright © 2010 John Wiley & Sons, Ltd.     

草酸铕颗粒微米层状颗粒的合成及其光学性能

在室温条件下, 以柠檬酸钠为辅助剂, 通过简单沉淀法合成了草酸铕Eu₂(C₂O₄)₃·10H₂O微米层状颗粒. 应用X射线衍射、X射线电子能谱、场发射扫描电子显微镜、光致发光光谱对Eu₂(C₂O₄)₃·10H₂O结构与性能进行了表征. 讨论了草酸铕微米层状颗粒可能的形成机理.     

Electron paramagnetic resonance of vanadyl ion impurities in crystalline solids

The electron paramagnetic resonance of VO²⁺ ion impurities has been studied in certain crystalline solids at ~ 9.45 GHz. VO²⁺ shows an isotropic spectra in Mg(ClO₄)₂·6H₂O, RbBr, RbI, CsCl, thiourea, NH₄HC₂O₄·$\text{1}\text{2}$H₂O and urea oxalate at room temperature, and has preferential orientation in MgSeO₄·6H₂O, KHC₂O₄, Rb₂SO₄ and (NH₄)₂M″(SeO₄)₂·6H₂O (M″ = Zn, Co) single crystals. The line broadening of the EPR spectra of VO²⁺ in (NH₄)₂Co(SeO₄)₂·6H₂O observed on cooling the crystal is explained on the basis of host spin lattice relaxation narrowing. The EPR spectra have been analysed and the spin-Hamiltonian parameters evaluated.     

Raman spectroscopic study of the arsenite mineral vajdakite [(Mo6+O2)2(H2O)2As3+2O5]·H2O

Raman spectra of vajdakite, [(Mo⁶⁺O₂)₂(H₂O)₂As O₅]·H₂O, were studied and interpreted in terms of the structure of the mineral. The Raman spectra were compared with the published infrared spectrum of vajdakite. The presence of dimolybdenyl and diarsenite units and of hydrogen bonded water molecules was inferred from the Raman spectra which supported the known and published crystal structure of vajdakite. Mo O and O H···O bond lengths were calculated from the Raman spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Vibrational Spectra of and Isotope Effect in Hydrogen Bonded Potassium Hydrogen Oxalate

The crystal structure of potassium hydrogen oxalate, KHC₂O₄, has been determined by Pedersen¹. There are infinite chains of hydrogen oxalate ions held together by short (2. 534 Å) hydrogen bonds. The O-D‥O distance of KDC₂O₄ derived from lattice constant changes is estimated to be about 0.005 Å larger than the O-H‥O distance which means that the isotope effect is small¹. We believe, however, on the ground of the infrared and Raman spectra of KHC₂O₄ and KDC₂O₄ repotted in this paper, that the isotope effect in these crystals is much larger.     

氯化苯并咪唑镧的荧光光谱

对新合成的化合物氯化苯并咪唑镧HCl₄·[C₇H₆N₂(H₂O)₂]₂La及其LaCl₃·5H₂O的水溶液进行了三维荧光光谱测定,讨论了HCl₄·[C₇H₆N₂(H₂O)₂]₂La在不同波长的光激发下的荧光特性,荧光强度与浓度的关系及标题化合物的上转换荧光,即在540nm绿光的激发下可以获得紫外光(290nm)和近紫外光(360nm).     

Raman spectroscopic study of the uranyl sulphate mineral jáchymovite (UO2)8(SO4)(OH)14· 13H2O

Raman spectra of jáchymovite, (UO₂)₈(SO₄)(OH)₁₄·13H₂O, were studied, complemented with infrared spectra, and compared with published Raman and infrared spectra of uranopilite, [(UO₂)₆(SO₄)O₂(OH)₆(H₂O)₆]·6H₂O. Bands related to the stretching and bending vibrations of (UO₂)²⁺, (SO₄)²⁻, (OH)⁻ and water molecules were assigned. U O bond lengths in uranyl and O H· · ·O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Spectroscopic studies of uranyl-acetonitrate complex formation in solutions

In the present work uranyl-acetonitrile complex formation is studied on the basis of analysis of vibrational (IR absorption and Raman) spectra of UO₂(NO₃)₂·6H₂O and UO₂(ClO₄)₂·7H₂O. From the present results and coordination critera for nitrate groups and acetonitrile, it is concluded that in the UO₂ (NO₃)₂·6H₂O-acetonitrile system, acetonitrile molecules are in the second coordination sphere of the uranyl ion. In a benzene solution of uranylperchlorate with added acetonitrile, acetonitryl is substituted for a water molecule in the first coordination sphere of the uranyl ion. In the coordination the vibration frequency of C≡H of acetonitrile (2240 cm⁻¹) is shifted by 21 cm⁻¹ to the shortwave region. Possible reasons for the relatively small change in this frequency are discussed. Belarusian State University, 4, F. Skorina Ave., Minsk, 220050, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 179–183, March–April, 1997.     

Raman and IR spectra of K4Nb6O17and K4Nb6O17·3H2O single crystals

Polarised Raman and IR spectra of K₄Nb₆O₁₇ and K₄Nb₆O₁₇· 3H₂O single crystals were measured. The obtained spectra are discussed using the factor group approach for the orthorhombic P2₁nb space group and assignment of bands to the respective motions of atoms is proposed. In particular, we have shown that the bands above 770 cm⁻¹ can be attributed to the stretching modes of short niobium–oxygen bonds, which are present in this material due to the pronounced layered structure, whereas the potassium atoms contribute to the bands observed below 180 cm⁻¹. Our studies have revealed that intercalation of water molecules leads to shifts, broadening and changes in intensity of some bands. These changes have been attributed to slight changes in the bond lengths and angles, interactions of the water molecules with K atoms and structural disorder introduced by the intercalated water molecules. However, the main structural framework was preserved. Copyright © 2010 John Wiley & Sons, Ltd.     

Vibrational spectra of lead(II) oxalate

The infrared and Raman spectra of anhydrous lead oxalate (PbC₂O₄) were recorded and discussed on the basis of its structural peculiarities. Some comparisons with other previously investigated metallic oxalates were made. Copyright © 2009 John Wiley & Sons, Ltd.     

Thermal Dehydration and Vibrational Studies of ZnK4(P3O9)2 · 6H2O

The thermal dehydration of ZnK₄(P₃O₉)₂ · 6H₂O was studied in the range 25–500°C by thermogravimetric analysis (TGA and DSC) and X‐ray diffraction. We found, based on the TGA and DSC scans, the dehydration of this salt takes place in three stages with a loss of the six water molecules. The infrared and Raman spectra of ZnK₄(P₃O₉)₂ · 6H₂O have been recorded and interpreted using a factor group analysis. The internal modes are assigned in terms of POP and PO₂ structural units using experimental and theoretical IR and Raman frequencies.     

The structure and vibrational features of proton disolvates in water–ethanol solutions of HCl: the combined spectroscopic and theoretical study

The infrared (IR) spectra of water–ethanol (EtOH) solutions of HCl are measured over a wide range of acid concentration at fixed H₂O―EtOH ratios (1 : 1, 1 : 2, and 1 : 40). In these systems, different proton disolvates with (quasi)symmetrical H‐bonds are formed. Their structure and vibrational features are revealed by the density functional theory method coupled with the polarizable continuum model of solvation. In dilute acidic solutions, the Zundel‐type H₅O₂⁺ ion is mainly formed. In concentrated HCl solutions, the ions (H₂O···H···O(H)Et)⁺ and (Et(H)O···H···O(H)Et)⁺ with the quasi‐symmetrical O···H⁺···O unit having O···O separation <2.45 Å appear. The first ion characterized by the IR‐intensive band around 1800 cm^?1 is mainly formed in the 1 : 1 water–ethanol systems. The second ion exists in the 1 : 2 and 1 : 40 water–ethanol systems. Its spectroscopic signatures are the groups of the IR‐intensive bands around 800 and 1050 cm^?1. In highly concentrated HCl solutions with the 1 : 40 water–ethanol ratio, a neutral Et(H)O···H⁺···Cl^? complex exists. Copyright © 2013 John Wiley & Sons, Ltd.     

On the luminescence of manganese(II) phosphates

Luminescent properties of manganese(II) phosphates prepared by thermal dehydration of Mn(H₂PO₄)₂·2H₂O have been studied. The emission spectrum consists of two bands whose relative intensity and spectral position depend on the chemical and crystalline structure of phosphates. The different courses of temperature quenching of luminescence intensity and excitation spectra of each emission band of Mn(H₂PO₄)₂·2H₂O, Mn(H₂PO₄)₂, MnH₂P₂O₇ and c-Mn₂P₄O₁₂ are discussed.     

Structure of ZnZrF<Subscript>6</Subscript> · <Emphasis Type="Italic">n</Emphasis>H<Subscript>2</Subscript>O (<Emphasis Type="Italic">n</Emphasis> = 6–2) and ZnZrF<Subscript>6</Subscript> crystallohydrates according to vibrational spectroscopy data

Fluoridezirconate crystallohydrates ZnZrF₆ · nH₂O (n = 6–2) and anhydrous ZnZrF₆ are investigated by vibrational spectroscopy and thermography. The influence of the hydrate number on the structure of the cationic and anionic sublattices of the crystallohydrates is studied. The changes in the strength of HOH···F and HOH···O hydrogen bonds of coordinated and outer-sphere water molecules occurring with variations in the hydrate number are determined by changes in the IR spectra. The IR spectra of ZnZrF₆ · nH₂O (n =6, 4) compounds, which have isolated complex anions [ZrF₆]^2– in their structure, revealed a band with two peaks in the range of 3470–3430 cm^–1, which corresponds to stretching vibrations of coordinated water molecules. The spectra of ZnZrF₆ · nH₂O (n = 5, 3, 2, 1) crystallohydrates with a polymeric structure show a high-frequency shift of this band, which corresponds to weakening of hydrogen bonds. The vibrations of crystallization water molecules involved in the network of strong O–H···F and O–H···O hydrogen bonds manifest themselves in the spectra of ZnZrF₆ · nH₂O (n =5, 3) crystallohydrates by broad structureless bands in the region of stretching, bending, and libration vibrations.     

The Studies of Enhanced Fluorescence in the Two Novel Ternary Rare-Earth Complex Systems

Two novel ternary rare-earth complexes SmL₅·L^’·(ClO₄)₂·7H₂O and EuL₅·L^’·(ClO₄)₂·6H₂O (the first ligand L = C₆H₅COCH₂SOCH₂COC₆H₅, the second ligand L^’ = C₆H₄OHCOO⁻) were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DSC, ¹HNMR and UV spectra. The detailed luminescence studies on the rare-earth complexes showed that the ternary rare-earth complexes presented stronger fluorescence intensities, longer lifetimes, and higher fluorescence quantum efficiencies than the binary rare-earth materials. After the introduction of the second ligand salicylic acid group, the relative emission intensities and fluorescence lifetimes of the ternary complexes LnL₅·L^’·(ClO₄)₂·nH₂O (Ln = Sm, Eu; n = 7, 6) enhanced more obviously than the binary complexes LnL₅·(ClO₄)₃·2H₂O. This indicated that the presence of both organic ligand bis(benzoylmethyl) sulfoxide and the second ligand salicylic acid could sensitize fluorescence intensities of rare-earth ions, and the introduction of salicylic acid group was a benefit for the fluorescence properties of the ternary rare-earth complexes. The fluorescence spectra, fluorescence lifetime and phosphorescence spectra were also discussed.     

Gadolinium orthophosphate weinschenkite type and phase change in rare earth orthophosphates

Some properties of rare earth orthophosphates have been determined by means of synthesis, X-ray diffraction, infrared absorption spectra, and Raman spectra measurements. The results are: (1) a synthesis of new compounds GdPO₄.2H₂O weinschenkite type, (2) the salt readily lost its water and changed from the weinschenkite to the xenotime form at about 300°C in air, (3) the change phase in rare earth orthophosphates showed that the weinschenkite phase can give rise to rhabdophane or xenotime phases, and (4) the orthorhombic form DyPO₄·1.5H₂O is explainable in terms of a mixture of rhabdophane and xenotime-structured material.     

Influence of oxalate anions on manganese electrodeposition in sulfate solution

The influences of oxalate anions on manganese electrodeposition in sulfate solution were investigated on the basis of cathode current efficiency, characterization of SEM-EDX and XRD, solution chemistry calculation, thermodynamics and electrochemical test. The experimental results show that the range of (NH₄)₂C₂O₄ was adjusted from 0 mol/L to 4.8?×?10^?3 mol/L. And 1.5?×?10^?3 mol/L (NH₄) ₂C₂O₄ was suitably used with initial pH 7.0. The characterization of SEM indicates that oxalate anions can improve the morphology of electrodeposited films. The electrodeposited films containing manganese were characterized and determined by EDX and XRD. The solution chemistry calculation of catholyte and oxalate anions shows that the main active species are MnSO₄, Mn(SO₄)2? 2, Mn²⁺, Mn(SO₄)C₂O2? 4, MnC₂O 4, Mn(NH₃)²⁺, and C₂O2? 4. The reaction trend between C₂O2? 4 and Mn²⁺ ions is confirmed by computation of reaction energy. Electrochemical test analysis indicates oxalate anions increase the overpotentials of hydrogen evolution reaction and manganese electrodeposition.     

Analysis of IR and Raman spectra of transition metal telluromolybdates

The work presents the IR and Raman spectra in the range 400–4000 cm^?1 of simple and double salts of hexamolybdotelluric (VI) acid of the general formula M₃[TeMo₆O₂₄]·nH₂O and (NH₄)_2xM_3?x [TeMo₆O₂₄]·mH₂O respectively, and of substitutive telluromolybdates with the wolframite structure MTe_yMo_1?yO₄, where M = Co, Zn, Ni and Mn. In this range the modes have been assigned to stretching vibrations of appropriate Mo-O bonds. Approximate values of force constants for these bonds have been computed and compared with the literature values reported for transition metal molybdates and ammonium heptamolybdate.