Study of the Absorption Characteristics of Transitions in the HOT 2υ2–υ2 Band of the 34SO2 Molecule

Russian Physics Journal - The absorption coefficient of the rovibrational 2υ2–υ2 band of the 34SO2 molecule localized in the region 350–850 cm–1 is studied for the first...     

Study of a High-Resolution Spectrum of the 5ν2 Band of the H2S Molecule

Russian Physics Journal -     

Analysis of the Vibrational-Rotational Structure of 2ν1, ν1 + ν3, and 2ν3 Bands of the D2Se Molecule

The absorption spectrum of the D₂Se molecule in the region of 2₁, ₁ + ₃, and 2₃ absorption bands is registered with a high-resolution Fourier spectrometer and is studied theoretically for a Hamiltonian model with allowance for resonant interactions among (200), (101), and (002) vibrational states.     

Spin-orbit splitting in the X2Π, a4Π, B2Π and H2Π electronic states of the NS radical

A model calculating the laser fields at a flat structureless surface taking into account the surface photoelectric effect is presented. The photon is p or transverse magnetic linearly polarized, continuous and its wave length is long, i.e. λ _vac  ≥ 12.4 nm. The sharp rise of the electron density at the interface generates an atomic scale spatial dependence of the laser field. In real space and in the temporal gauge, the vector potential A of the laser is obtained as a solution of the classical Ampère-Maxwell and the material equations. The susceptibility is a product of the electron density of the material system with the surface and of the bulk tensor and non-local isotropic (TNLI) polarizability. The electron density is obtained quantum mechanically by solving the Schrödinger equation. The bulk TNLI polarizability including dispersion is calculated from a Drude-Lindhard-Kliewer model. In one dimension perpendicular to the surface the components \hbox{$\mathcal{A}_x(z,\omega)$} ?? _x (z,ω) and \hbox{$\mathcal{A}_z(z,\omega)$}?? _z (z,ω) of the vector potential are solutions of the Ampère-Maxwell system of two coupled integro-differential equations. The model, called vector potential from the electron density-coupled integro-differential equations (VPED-CIDE), is used here to obtain the electron escape probability from the power density absorption, the reflectance, the electron density induced by the laser and Feibelman’s parameters d _∥ and d _⊥. Some preliminary results on aluminium surfaces are given here and in a companion paper the photoelectron spectra are calculated with results in agreement with the experiment.     

Assignment of the Ammonia ν2(2a->2s) Rotational MIR Laser Transitions Pumped by a Tunable CO2 Laser

In this work is reported the assignment of the NH3 MIR rotational laser lines previously observed inside the 2₂ vibrational level. Some of them are due to the one photon pump of the hot band 1s->2a, the most part is assigned to off resonance two photon pumping (0a->1s->2a) induced at intermediate detunings as large as 600GHz     

Determination of the spatial dependence of the complex components of the tensor \hat \chi ^{(2)} (z, ω 1 + ω 2; ω 1, ω 2) of a medium with one-dimensional inhomogeneity using a biharmonic wave

It is proven that the spatial profiles of different components of the complex quadratic susceptibility tensor $\hat \chi ^{(2)}$ (z,?? ₁+?? ₂; ?? ₁, ?? ₂), which is responsible for the generation of sum-frequency wave in a plate with one-dimensional inhomogeneity, can be reconstructed unambiguously. A reconstruction technique is proposed. To implement it, one has to direct a plane biharmonic wave with monochromatic components at frequencies ?? ₁ and ?? ₂ onto a plate and measure (in some range of the angles of incidence) the complex amplitude of the sum-frequency wave reflected from the plate. Changing the plane of incidence of the initial wave and (or) the polarization of its monochromatic components, one can determine the coordinate dependences for more than half of the components of $\hat \chi ^{(2)}$ (z,?? ₁+?? ₂; ?? ₁, ?? ₂). This reconstruction can be performed if the symmetry of the plate medium provides a diagonal form for its linear permittivity tensor. The technique proposed implies measurement of the intensities of the sum-frequency waves generated under special conditions using an auxiliary reference plate; this approach allows one to do without complex phase measurements.     

Theoretical calculation of the triple differential cross sections of the 2p orbital of argon in a coplanar highly asymmetric（e,2e） reaction

The triple differential cross sections of the 2p electron of argon in a coplanar highly asymmetric geometry have been calculated with the modified distorted wave Born approximation (DWBA) and the target Hartree－Fock approximation methods. The damping polarization of the semi-classical short-range potentials and the M_ee factor are included in the distorting potentials of the modified DWBA. Theoretical results are compared with a recent experiment. The dynamic mechanism of inner shell ionization in a coplanar highly asymmetric geometry (e, 2e) reaction are also discussed.     

The Lie algebra of the sl(2, ℂ)-valued automorphic functions on a torus

It is shown that the Lie algebra of the automorphic, meromorphic sl(2, )-valued functions on a torus is a geometric realization of a certain infinite-dimensional finitely generated Lie algebra. In the trigonometric limit, when the modular parameter of the torus goes to zero, the former Lie algebra goes over into the sl(2, )-valued loop algebra, while the latter goes into the Lie algebra (A ₁ ⁽¹⁾ )/(centre).     

Influence of D-state in 4He on S Factor for the 2H（d, γ）^4He Reaction

We employ a direct capture method to study the influence of D-state in ^4He on S factor for the ^2H（d,γ）^4He reaction, in which the D-state component of the colliding deuterons and D-state component in ^4He ground state are considered. The parameters of Woods-Saxon （WS） potentials are obtained by reproducing the binding energy of d-d （i.e. ^2H-^2H） system, and d-d elastic scattering phase shifts calculated by the resonating group method. The theoretical results are in good agreement with the experimental data at Ec.m〈 3 MeV. The impact of the D state probability in ^4He on the extrapolated value of the astrophysical S factor for ^2H（d, γ）^4He reaction is discussed.     

Mechanism of the excitation of single pure mode L（0, 2） and its interaction with the defect in a hollow cylinder

Guided elastic waves have a great potential in pipe inspection as an efficient and low-cost nondestructive evaluation （NDE） technique, among which the wave of mode L（0, 2） receives a lot of attention because this mode is the fastest mode in a weakly dispersive region of frequency to minimize dispersion effects over a long distance and sensitive to the defects distributed circumferentially. Though many experimental and numerical researches have already been carried out about the excitation of L（0, 2） and its interaction with the defect in a hollow cylinder, its excitation mechanism has not been clarified yet. In this paper based on the transient response solution of the hollow cylinder, derived by the method of eigenfunction expansion, the theory about the exciting mechanism of mode L（0, 2） is advanced and the effects of the spatial distribution, vibration frequency and direction of the external force on the excitation are discussed. And the pure mode L（0, 2） is excited successfully under the parameters obtained through theoretical analysis. Furthermore, its interactions with some kinds of defects in hollow cylinders are simulated with the method of finite element analysis （FEA） and the results agree well with those obtained by other researchers.     

Determination of the spatial profiles of all components of the quadratic susceptibility tensor \hat \chi ^{(2)} (z, 2ω; ω, ω) of a one-dimensionally inhomogeneous absorbing medium

For a one-dimensionally inhomogeneous plate whose linear dielectric properties are also inhomogeneous and are characterized by a diagonal permittivity tensor, it is proved that the spatial profiles of all components of the complex quadratic susceptibility tensor $\hat \chi ^{(2)} $ (z, 2??; ??, ?? responsible for the second harmonic generation can be uniquely determined, and an appropriate method is proposed. To implement this method, one should measure the complex coefficient of transformation of a fundamental plane wave incident on the plate into a reflected second-harmonic wave in a certain range of angles of incidence. By varying the plane of incidence of the wave and (or) its polarization and measuring the coefficients of transformation into s- and p-polarized waves of double frequency, one can uniquely determine the spatial profiles of all components of the quadratic susceptibility tensor. The method involves the measurement of the intensities of the second-harmonic waves generated under special conditions with the use of two auxiliary reference plates and thus allows one to avoid complicated phase measurements.     

First-principles study of the effect of iron on the crystal structure,stability and chemical bonding in the β-based AlCu ordered η2-phase and the pretransition state of a solid solution

First-principles calculations showed that the thermodynamic stability of β-based ordered η₂-AlCu phase doped with Fe is due to iron substitution in the copper sublattice (Fe_Cu), which corresponds to the maximum number of Fe–Al bonds in the first cubic coordination polyhedron. This iron localisation leads to stable ω-like atomic displacements and pentagonal Al-nets in the (010) plane of η₂-AlCu(Fe). This phase with iron substituting copper (e/a?=?1.925) is an energetically preferred η-based non-canonical approximant of the icosahedral phase (e/a?=?1.86). The energy gain for the Fe_Cu position is determined by strong covalent Fe3d–Al3p bonding, while there is a weak Fe3d–Cu4s3d hybridisation for the Fe_Al substitution. Using a composite cluster model, we demonstrate that short-range order in the pretransition state of the β-Al–Cu–Fe solid solution observed prior to the precipitation of η-phase is stabilised due to formation of Fe–Al bonds in the first cubic coordination polyhedron of the composite cluster.     

The role of vacancy,impurity,impurity-vacancy complex in the kinetics of LiNH2 complex hydrides:a first-principles study

This paper studies first-principles plane-wave pseudopotential based on density functional theory of hydrogen vacancy,metal impurity,impurity-vacancy complex in LiNH 2,a promising material for hydrogen storage.It finds easy formation of H vacancy in the form of impurity-vacancy complex,and the rate-limiting step to the H diffusion.Based on the analysis of the density of states,it finds that the improvement of the dehydrogenating kinetics of LiNH 2 by Ti catalysts and Mg substitution is due to the weak bonding of N-H and the new system metal-like,which makes H atom diffuse easily.The mulliken overlap population analysis shows that H vacancy leads to the H local diffusion,whereas impurity-vacancy complexes result from H nonlocal diffusion,which plays a dominant role in the process of dehydrogenation reaction of LiNH 2.     

Estimation of the solubility product of hydrocalumite–hydroxide,a layered double hydroxide with the formula of [Ca2Al(OH)6]OH·nH2O

From aqueous NaOH/Ca(OH)₂/NaAl(OH)₄ mixtures, after allowing short reaction times we observed the precipitation of Ca(OH)₂(s) at lower, and a mixture of Ca(OH)₂(s) and a layered double hydroxide, hydrocalumite (HC) at higher aluminate concentrations. From the maximum aluminate concentration, at which the equilibrium solid phase is still portlandite (i.e., further increase in the aluminate concentration results in HC appearing in the precipitate beside the portlandite), the concentration based solubility products of two polymorphs of HC with the formula of [Ca₂Al(OH)₆]OH·nH₂O (differing in n) has been estimated and was found to be log L_HC=−11.4 at 25 °C and −12.1 at 75 °C, respectively (where L_HC=[Ca²⁺]²[Al(OH)₄⁻][OH⁻]³) and at constant ionic strength (I=1 M NaCl). To the best of our knowledge, this is the first published estimate for the solubility product of hydrocalumite. Additionally, from the composition obtained for NaOH/Ca(OH)₂/NaAl(OH)₄ mother liquors in equilibrium with Ca(OH)₂(s), attempts were made to extract the formation constant of the ion pair CaAl(OH)₄⁺. It was found, that the effects caused by the supposed formation of this solution species are too small to be reliably determined, which allowed an upper estimate for its formation constant, K, to be suggested in the temperature range of 25–75 °C (K<200 and 40 M⁻¹ at 25 and 75 °C, respectively).     

Dissociative Chemisorption of an H2（v,j） Molecule on Rigid Ni （100） Surface： Dependence on Surface Topologies and Initial Rovibrational States of the Molecules

The H2(v,j) Ni(100) collision system has been studied to understand the effects of the surface sites and initial rovibrational states of the molecule on molecule-surface interactions, by a quasiclassical molecular dynamic simulation method. Dissociative adsorption of an H2 molecule on the rigid Ni(100) surface is investigated at topologically different three sites of the surface. Interaction between the molecule and Ni surface was described by a London-Eyring-Polani-Sato (LEPS) potential. Dissociative chemisorption probabilities of the H2(v, j) molecule on various sites of the surface are presented as a function of the translation energies between 0.001-1.0eV. The probabilities obtained at each collision site have unique behaviour. At lower collision energies, indirect processes enhance the reactivity, effects of the rotational excitations and impact sites on the reactivity are more pronounced. The results are compared with the available studies. The physical mechanisms underlying the results and quantum effects are discussed.