Reorganization of the cluster state in a C60/N-Methylpyrrolidone/water solution: Comparative characteristics of dynamic light scattering and small-angle neutron scattering data

Data on dynamic light scattering from cluster solutions of C₆₀ fullerenes in N-methylpyrrolidone (NMP) and its mixture with water are analyzed. Initial C₆₀/NMP solutions kept for two weeks (i.e., fresher than those analyzed previously) are considered, where the effect of cluster-state reorganization after adding water is recorded more reliably. Based on the size-distribution functions of the clusters, obtained from dynamic light scattering data, model curves of small-angle neutron scattering are calculated and compared with the experimental data.     

Electric field modulated Raman scattering in CdS

We have observed electric field modulated Raman scattering by A₁ LO phonons in CdS. The field induced scattering is observed with a geometry in which Raman scattering by A₁ LO phonons is normally allowed. The interference of the field induced and allowed terms in the transition susceptibility leads to a modulated Raman scattering intensity proportional to the applied field. This is contrasted with data previously reported on field induced Raman scattering by E₁ LO phonons in a configuration in which the Raman scattering is normally forbidden and in which there is no interference between linear wavevector dependent and field induced terms in the transition susceptibility. Electric field effects on Raman scattering by TO phonons and by 2 LO phonons is also discussed.     

Raman scattering by optical phonons and polaritons in CuCl

We present data on forward and backward scattering in CuCl at liquid N₂ temperature. Peaks at 146 and 172 cm^-1 which appear in both forward and backward scattering spectra are attributed to other than first order scattering by optical phonons. The data on polarition scattering indicate that the atomic displacement contribution to the scattering by TO phonons is rather small. From the experimentally determined polarition dispersion curve we obtain a value of 174 ±2.5 cm^-1 for ω_T and a value of 5.3 for ?_S.     

Representation of supercharges over the scattering data for super-sine-Gordon system

We determine the form of the superchargesQ ₁ andQ ₂ in terms of the scattering data for the super-sine-Gordon equation. The technique is to ascertain the effect of supertranslation on the scattering data used in the inverse scattering transform. The same result was obtained by Kulish and Tsypleyv from the Riccatti equation by expanding in A.     

The scattering of hydrogen,deuterium, and the rare gases from silver (111) single crystals

The scattering of hydrogen, deuterium, and the rare gases from the (111) face of silver has been studied at ultrahigh vacuum. The surfaces were prepared by argon ion bombardment and high temperature annealing. Incident angles between 20° and 65° and surface temperatures between room temperature and 573°K have been investigated. The scattering data exhibit quasi-elastic scattering (He, H₂, D₂), inelastic scattering (Ne, Ar, Kr), and trapping dominated scattering (Xe). Identification of these scattering regimes correlates with D/kT_g and is consistent with similar data from Pt(111) and W(110). The separate effects of microscopic surface roughness and thermal roughening have been identified and thermal attenuation in the elastic regime correlated with dynamical interactions rather than thermal roughening. Trapping and rotational coupling are discussed. Comparison of the data with scattering from epitaxial (111) silver indicates that the epitaxial surfaces are significantly more disordered than the single crystal surfaces.     

反散射理论应用于e-H2O碰撞

运用反散射方法研究了ｅ－Ｈ₂Ｏ碰撞。从ｅ－Ｈ₂Ｏ弹性散射微分截面的实验数据出发，运用反散射方法，ｅ－Ｈ₂Ｏ相互作用的球平均势已被导出，它是复数的，而且含有非定域的成分。所得的势能给出非常符合实验数据的结果。 关键词：     

Structure of amyloid aggregates of lysozyme from small-angle X-ray scattering data

The structure of filament amyloid aggregates of hen egg white lysozyme in water has been investigated by the small-angle X-ray scattering method. The experimental data are described by different cylindrical models, among which the best agreement is reached with the long helix model. A comparison of the results with the small-angle neutron scattering data reveals the influence of the heavy component of the solvent (a H₂O/D₂O mixture) on the structure of the filaments.     

Theory of diffusion in premelting systems

Summary The diffusion in premelting films and surfaces is described by the Fokker-Planck equation with a periodic potential whose amplitude depends on the temperature and vanishes at the bulk melting temperature. The self-part of the dynamic structure factor is calculated and the results are compared with neutron scattering data from CH₄ premelting films adsorbed on MgO and with atom scattering data from the (110) surface of Pb. In honour of Prof. Fausto Fumi on the occasion of his retirement from teaching.     

Electron correlation effects in N2 and CO studied by X-ray scattering and CISD calculations

Total X-ray scattering intensities σ_ee(q) for N₂ and CO have been measured as a function of momentum transfer using the energy dispersive method. Novel procedures to extract accurate σ_ee(q), which eliminate effects of polarization, inelastic scattering, anomalous dispersion, and molecular vibration, have been proposed. A simplified theoretical treatment based on configuration interaction singles and doubles (CISD) calculations has been suggested. This procedure makes it possible to apply combined theoretical and experimental X-ray scattering studies to larger molecules. The inclusion of f and g functions is crucial, and the σ_ee(q) calculated with the cc-pVQZ[5s4p3d2f1g] basis set almost reproduces the data based on more elaborate MR-CISD calculations within the experimentally most relevant region of up to q ? 3 au. In contrast to experimental electron scattering data, the X-ray scattering intensities agree well with the computed results.     

Cu(100)表面上H2/D2散射的六维态-态量子动力学研究：位点平均模型的有效性

基于由optPBE-vdW密度泛函计算的数千个数据点拟合得到的精确的神经网络势能面,本文采用含时波包方法对H₂/D₂在刚性Cu(100)表面上的态-态散射进行了六维量子动力学计算. 与以往的理论和实验比较了H₂和D₂在Cu(100)中的振转(非)弹性散射的结果. 特别是通过将六维的(非)弹性散射几率与从十五个位点加权平均四维几率的结果比较,测试了在该体系中位点平均近似模型的有效性. 具体来说,位点平均模型很好地重现了振动弹性散射几率,尽管对于高能下的振动非弹性散射结果没那么好. 结果说明在未来研究重双原子或多原子分子从金属表面的态-态散射动力学时,可以使用位点平均模型来降低全维计算过高的成本.     

The scattering of slow neutrons by cobalt

Different techniques have been used to determine with slow neutrons the coherent scattering amplitude b_c and the total scattering cross-section σ_sc of Co. We found values for the bound atom b_c=2.78+0.04 fm and for the free nucleus σ_sc=5.95+0.05 barns.From these quantities, the spin state scattering amplitudes b₊ and b_? corresponding to the compound nucleus states of spin I+1/2 or I?1/2 have been determined as b₊=?2.78±0.04 fm and b_?=+9.91±0.06 fm. These results are not in agreement with previous data, but they are found to be consistent with data obtained from resonance parameters.     

Deep-UV Rayleigh scattering of N2, CH4 and SF6

Rayleigh scattering room temperature cross-section values of N₂, CH₄ and SF₆ have been obtained between 198 and 270 nm by combining cavity ring-down spectroscopy (CRDS) and pressure ramp measurements. The experimental data have been fitted to a functional representation, describing the ～1/λ⁴ like behaviour of the Rayleigh scattering cross section over a wide wavelength range. The resulting values are compared with numerical predictions, based on refractive indices and molecular anisotropy data available in the literature. From this, values of molecular volume polarizability α_vol and depolarization ratios are derived. It is found that the optical extinction for all three gases is governed by Rayleigh scattering for wavelengths down to 200 nm. No absorption onsets in the specified deep-UV region have been observed.     

Microscopic collective dynamics of atoms in the amorphous metallic alloy Ni33Zr67

The structural properties and microscopic collective dynamics of atoms in the amorphous metallic alloy Ni₃₃Zr₆₇ are studied using molecular dynamics simulations with a pair-additive model potential. The calculated equilibrium structural and dynamic characteristics are compared with experimental data on neutron diffraction and inelastic X-ray scattering. Theoretical analysis of the structural relaxation of microscopic density fluctuations for amorphous metallic alloys is performed within the Lee’s recurrent relation approach. The results of theoretical calculations for the intensity of scattering I(k, ω) for the amorphous metallic alloy Ni₃₃Zr₆₇ are in good agreement with the results of computer simulation and experimental inelastic X-ray scattering data. The low-frequency excitations observed in the longitudinal current spectra are related to the vibrational motions of individual atom clusters, which include Ni and Zr atoms.     

Structural Aspects of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript> Magnetic Nanoparticles According to X-Ray and Neutron Scattering

Structural aspects of powders containing magnetic nanoparticles Fe₃O₄/CoFe₂O₄ with the anticipated “core-shell” structure are considered by means of comparative analysis with individual particles of Fe₃O₄, CoFe₂O₄ in accordance of data obtained from X-ray powder diffraction and small-angle scattering of X-ray (synchrotron) radiation and neutrons. It is shown that magnetic particles in the powders under study have a strong polydispersity and form complex aggregates. Characteristic sizes of the crystallites, as well as a ratio of magnetite to cobalt-ferrite in the composition of the Fe₃O₄/CoFe₂O₄ particles were evaluated from the analysis of the diffraction peaks. Аnalyzing the data on small-angle scattering, the dimensional characteristics of particles and aggregates, as well as the volume fraction of the last ones in the powders, have been obtained. Fractal dimensions of aggregates are determined. A significant difference is observed in the scattering on Fe₃O₄/CoFe₂O₄ particles and the total scattering consisting of partial contributions to scattering on individual magnetite (Fe₃O₄) and cobalt-ferrite (CoFe₂O₄) powders, which does not exclude the formation of the “core-shell” structure.     

Quantum theory of molecule-surface scattering: Rotational transitions

The quantum theory of atomic scattering from hard surfaces, previously developed, is extended to cover molecular scattering, taking into account rotational transitions. Two methods (a perturbative and a nonperturbative approach) are considered: the former is applied to H₂ scattering, the latter to HD scattering from LiF. A comparison with recent experimental data gives satisfactory results when a potential well of 440 K and a corrugation amplitude of 0.17 Å are assumed for the H₂ — LiF interaction.     

Electrical resistivity of intercalated molybdenum disulfide

The electrical resistivity of hexagonal synthetic single crystals and natural crystals of MoS₂ intercalated with alkali metals (K, Rb and Cs) has been measured. The average room-temperature values is 0.004 ω-cm, and the best single crystal data on K_0.4MoS₂ showed at T^1.5 temperature behaviour characteristic of acoustical phonon scattering for a quasi-isotropic metal. The metallic behaviour and scattering mechanism are discussed.     

Suppression of the photoinduced light scattering in LiNbO3:Fe by redox treatment and incoherent homogeneous illumination

In this paper, the redox treatment and incoherent homogeneous illumination were tried for the suppression of the photoinduced light scattering in LiNbO₃:Fe. Meanwhile, the effects of both the redox treatment and incoherent homogeneous illumination on the holographic storage properties of LiNbO₃:Fe were also studied. Our experimental data show that the reduction treatment sacrifices the diffraction efficiency for the suppression of photoinduced light scattering in LiNbO₃:Fe. By contrast, incoherent homogeneous illumination with the wavelength of 460 nm is efficient to suppress the photoinduced light scattering without any tradeoff on the holographic storage performance of LiNbO₃:Fe. The superiority of homogeneous illumination over the reduction treatment was attributed to the untouched acceptor concentration under the homogeneous illumination.     

Scattering properties of the ultracold 133Cs2 triplet state

The elastic scattering properties of ultracold 133Cs2 triplet state are investigated in detail.We construct a potential curve of the 133Cs2 triplet state,based on the latest ab initio molecular potential data and show how the scattering parameters are obtained by using three methods:the Numerov method,the semiclassical method and the variable phase method,where the scattering lengths of the 133Cs2 triplet state,i.e.301.79a0,300.67a0 and 310.81a0 are obtained respectively,with a0 being the Bohr radius.We also calculate the effective range and the number of bound states for the 133Cs2 triplet state.Our results are in agreement with the recent experimental data and the theoretical calculations.This confirms that the results of the scattering properties of the ultracold 133Cs2 triplet state,calculated by using these three methods,are reliable.     

A Mössbauer study of the silica-like structures of FePO4 and (Al0.67Fe0.33)PO4

Summary Samples of FePO₄ and (Al_0.67Fe_0.33)PO₄ have been investigated by M?ssbauer spectroscopy. The data obtained on quadruple splittings are in agreement with neutron scattering and XRD data on (Al, Fe)O₄ tetrahedra structures.