Magnetic circular dichroism and absorption spectra of d° tetrahedral oxyanions and thioanions: MoS4 2-, MoO4 2-, WS4 2-, ReS4 -, VS4 3-, VO4 3- and OsO4

Absorption and magnetic circular dichroism spectra have been measured for the tetrahedral d° ions MoS₄ ^2-, MoO₄ ^2-, WS₄ ^2-, ReS₄ ^-, VS₄ ^3-, VO₄ ^3- and OsO₄ in the visible and ultra-violet spectral range. Comparison of the experimentally obtained MCD parameters with regard to their relative signs leads to the conclusion that probably the first two allowed longest wavelength electronic transitions of all these species have the same assignment (i.e., t ₁ →2e and 3t ₂ →2e, which seems likely on energetic grounds). An estimation of the MCD parameters by using eigenvectors from recently published molecular orbital treatments gave contradictory results.     

Effect of pressure on the solubilities of LiF,NaF, KCl,NH4, Cl,K2SO4, (NH4)2SO4, and ZnSO4·7H2O in water at 298.15 K

Abstract

Solubilities of seven inorganic compounds in water were measured at 298.15 K and up to 350 MPa. The solubilities of K₂SO₄, LiF, NaF, and KCI increased with increasing pressure, those of NH₄Cl and (NH₄)₂SO₄ decreased, and that of ZnSO₄·7H₂O showed almost no dependence on pressure. From the slopes of these solubility curves at 0.1 MPa, we estimated the volume changes accompanying the dissolution of the solutes. These values coincided with the volume differences between the partial molar volume at saturation and the molar volume of the crystal within ca. ± 1 cm³ mol^?.     

Liquid-crystalline properties of 4-alkyl-, 4-alkyloxy and 4-halogene-4′-hydroxyazobenzene alkyloates

Twenty one esters, 4-alkyl-, 4-alkyloxy-, 4-nitro- and 4-halogene-4′-hydroxyazobenzne alkyloates have been synthesised. Basing on the DSC calorimetry and polarizing microscopy liquid- crystalline polymorphism was investigated. Five types of mesophases were identified: nematic, smectics A, C, F and unknown X (probably G).     

双超核ΛΛ5H,ΛΛ5He,ΛΛ4H,ΛΛ4He的研究

用少体理论方法对双Λ超核ΛΛ5He(ΛΛ5H)及ΛΛ4He(ΛΛ4H)的结合能进行了计算．结果表明,ΛΛ5He(ΛΛ5H)存在稳定的束缚态. 它们的双Λ结合能分别为对的研究的初步结果表明，它存在束缚态但相对于衰变不稳定．至于，结论是它不存在束缚态．     

Experimental study of the 4fn → 4fn and 4fn → 4fn-15d1 transitions of the lanthanide diiodides LnI2 (Ln=Nd, Sm, Eu, Dy, Tm, Yb)

The diffuse reflectance and photoluminescence (PL) spectra of NdI(2), SmI(2), EuI(2), DyI(2), TmI(2) and YbI(2) were measured between 225 and 12?500?nm in order to determine their 4f(n)?→?4f(n-1)5d(1) optical bandgaps. The results were compared with those obtained using an empirical model of the electronic structure of LnI(2). The results can be used to explain the lanthanide valency and crystalline structure changes of other lanthanide diiodides such as PrI(2).     

G-, F-, and ∊-Matrices for XY4Z Molecules of C4V Symmetry

XY₄ Z molecules or ions with a square-pyramid structure (C_4v) are relatively rare. This explains the infrequency of investigations of their vibrational spectra, with analysis in normal coordinates and computation of the mean-square amplitudes of vibration.     

Critical (Φ4)3,ε

The Euclidean (⁴)_3, model in R³ corresponds to a perturbation by a ⁴ interaction of a Gaussian measure on scalar fields with a covariance depending on a real parameter in the range 01. For =1 one recovers the covariance of a massless scalar field in R³. For =0, ⁴ is a marginal interaction. For 0<1 the covariance continues to be Osterwalder-Schrader and pointwise positive. We consider the infinite volume critical theory with a fixed ultraviolet cutoff at the unit length scale and we prove that for >0, sufficiently small, there exists a non-gaussian fixed point (with one unstable direction) of the Renormalization Group iterations. We construct the stable critical manifold near this fixed point and prove that under Renormalization Group iterations the critical theories converge to the fixed point. Partially supported by NSERC of CanadaLaboratoire Associé au CNRS. UMR 5825Partially supported by CNR, G.N.F.M. and MURST     

Studies on binary mixtures of 4-pentyloxy-4′-cyanobiphenyl with three 4, 4′-di(alkoxy)azoxybenzenes

Eighteen binary mixtures of 4-pentyloxy-4′-cyanobiphenyl (5OCB) and 4, 4′-di(alkoxy)azoxybenzenes (nOAB) with n = 5, 6, and 7 at different concentrations have been studied in detail. Over a wide concentration range, induced SmA phase was observed in all the mixtures except in one. In most of the mixtures, the refractive indices no, ne, and Δn lie between the values of pure components. The optical birefringence of the mixtures is found to decrease non-additively with concentration. The molecular polarizability anisotropy and the orientational order parameter <P₂> of the mixtures were calculated. Nature of variation of polarizability anisotropy with concentration is similar to that of Δn. In allmixtures <P₂> is more in smectic phase than in nematic phase and it also shows non-additive behaviour. Observed <P₂> values of the mixtures were compared with McMillan’s and Maier-Saupe theoretical values and good agreement is found in some mixtures. The transition temperatures obtained by fitting <P₂> data to McMillan’s theory agree with the observed values within a few degrees. Ratio of elastic constants K₃₃ and K₁₁ is determined for mixtures having nematic phase and found to diverge at T_NA transition point.     

4,4‘,4“,4”’—磺酸酞菁镓的二聚常数的测定

采用光度法测定了４，４＇，４＂，４＂＇－磺酸酞菁镓（ＴｓＰｃＧａ）的二聚平衡常数Ｋｄ，讨论了ＰＨ值，离子强度、水温度等因素对Ｋｄ的影响。     

Structure and properties of the anions MF4−, MCl4− and MBr4− (M = C,Si, Ge)

Density functional theory (DFT), Møller–Plesset (MP2) and coupled cluster with single and double substitutions including non-iterative triple excitations (CCSD(T)) calculations on the anions MX₄^?, with M = C, Si, Ge and X = F, Cl, Br, show that GeF₄^?, SiCl₄^?, GeCl₄^? and SiBr₄^? prefer a C_2v conformation, but CCl₄^? is an elongated C_3v structure. CBr₄^? has T_d symmetry in MP2, but is slightly more stable in elongated C_3v form with DFT and CCSD(T). GeBr₄^? has T_d symmetry. CF₄^? and SiF₄^? are unstable with respect to loss of an electron. Vertical electron affinities (EAs) are negative also for CCl₄ and SiCl₄, and close to zero for GeF₄ and SiBr₄. Adiabatic EAs range from 0.47 eV for SiCl₄ to 1.78 eV for GeBr₄. The lowest excited states at T_d symmetry are ²T₂ resonances with energies of 2.1–3.5 eV, resulting from excitation of the a₁ singly occupied molecular orbital to vacant t₂ orbitals. Vertical excitation energies (VEEs) and vibrational frequencies are given for the most stable anionic geometries. Comparison with experimental VEEs for CCl₄^? is made. From dissociation energies of MX₄, MX₄^?, MX₃ and MX₃^?, appearance energies of X^?, MX₃^?, X₂^? and MX₂^? were calculated. Most were found to be in reasonable agreement with experimental values. Theoretical spin densities and g-factors have been compared with experimental results available for CCl₄^?, SiCl₄^? and GeCl₄^?.     

4 ,4′-二巯基二苯醚分子的电子输运性质研究

利用从头算方法和弹性散射格林函数理论,研究了4 ,4′-二巯基二苯醚分子的电输运性质.计算表明,当外加偏压少于0 .9 V时,该分子器件不导电.当外加偏压进一步增加时,该分子器件的电导呈现出平台特征.由于中间氧原子的存在,相对于4 ,4′-二巯基联苯分子来说,该分子的导电特性较差.     

Synthesis,characterization and phase transition studies in 4-hexyloxy benzylidene 4’-alkoxyanilines

Synthesis and the characterization through polarizing optical microscope (POM) textures in number of 4-hexyloxy benzylidene 4’-alkoxyanilines, 6O.Om with m = 4, 6 to 10 liquid crystalline materials are carried out. Furthermore, the density and thermal expansion coefficient results reveal that the phase transitions present, viz., isotropic–nematic, nematic–SmC and SmC–SmI show first-order nature as expected. The transition temperatures obtained thorough the differential scanning calorimetry is found to be in agreement with the literature data. The first two compounds exhibit only the nematic phase while the next four compounds show enantiotropic SmC phase as per the literature data. The compound with m = 10 exhibits monotropic SmI phase. However, we, the authors, are able to observe this phase in addition to SmC and nematic through POM only as per the literature. The parameters calculated across the phase transitions and in the phases are in agreement with the body of the data available.     

Ionic transport in the Na2SO4Na2WO4 and Na2SO4M2(SO4)3 (M=La,Dy, Sm,In) systems

Premelted, predried Na₂SO₄, premelted Na₂WO₄, Na₂SO₄Na₂WO₄ composites and Na₂SO₄M₂(SO₄)₃ (M = La, Dy, Sm, In) have been studied by means of X-ray diffraction, DTA and electrical conductivity measurements. The high temperature, highly conducting Na₂SO₄ phase I has been successfully stabilised at room temperature; the Na₂SO₄ containing 4 mole% La₂(SO₄)₃ exhibits the highest conductivity (σ) and lowest activation energy (E_a) (σ=1.08 × 10⁻³ω⁻¹ cm⁻¹ at 290°C and E_a=0.50 eV) and therefore this system appears promising for further development.     

Pseudo-Jahn–Teller effect in Si4X4 (X = F,Cl, Br,I) molecules: a theoretical investigation

ABSTRACT

The variability of planar rings in Si₄X₄ (X?=?F, Cl, Br, I) molecules caused by the pseudo-Jahn–Teller impact (PJTE) was evaluated as an original PJTE work. Optimisation and the following frequency calculations in these molecules illustrated that in high-symmetry planar (with D_4h symmetry) geometry, all of these compounds were unstable and their structures were puckered to lower C_2h symmetry stable geometry. Furthermore, the vibronic coupling interaction between ¹A_1g ground and the first ¹E_g excited states through (¹A_1g?+?¹E_g) ? e_g PJTE problem was the cause of non-planarity of the four-member ring and the symmetry breaking phenomenon in those series. The calculated gaps (Δ) between the ground state and the E_g excited state, the vibronic coupling (F) and ground state primary force constant values (k₁) were obtained from the numerical fitting of the ground state adiabatic potential energy surface with the analytical expressions of these molecules. Finally, natural bond analysis (NBO) was used for the design of the strongest interaction and natural atomic charges of these structures.     

CosmologicalΦ 4,Φ 6, and Sine-Gordon theories with broken symmetry

Particular solutions to the Einstein equations with cosmological constant are presented and discussed for an isotropic, spatially homogeneous, and spatially flat space-time in the case that the matter fields are ⁴, ⁶, and sine-Gordon fields.