Resonance Rayleigh scattering and resonance nonlinear scattering of the palladium(II)–acetazolamide chelate with eosin Y and their analytical application

A simple, rapid, and convenient method based on ion association for the determination of acetazolamide has been developed. Acetazolamide can react with palladium(II) to form cationic chelate at sodium acetate–acetic acid buffer solution, which can further react with eosin Y to form an ion association complex. As a result, the resonance Rayleigh scattering, second-order scattering, and frequency doubling scattering intensities are enhanced. Analytical wavelengths of resonance Rayleigh scattering, second-order scattering, and frequency doubling scattering located at 298, 558, and 338?nm, and the linearity range are 0.014–2.5, 0.034–2.5, and 0.119–2.4?µg?mL^?1 respectively. In addition, the optimum conditions and the effect of coexisting substances are investigated. Besides, the structure of ion association complex, the reaction mechanism and the reasons for the enhancement of scattering are discussed through infrared spectra, absorption spectra, and quantum chemical calculations.     

Theory of multinonlinear media and its application to the soliton processes in ferrite–ferroelectric structures

A theory is developed to describe the wave processes that occur in waveguide media having several types of nonlinearity, specifically, multinonlinear media. It is shown that the nonlinear Schrödinger equation can be used to describe the general wave process that occurs in such media. The competition between the electric wave nonlinearity and the magnetic wave nonlinearity in a layered multinonlinear ferrite–ferroelectric structure is found to change a total repulsive nonlinearity into a total attractive nonlinearity.     

On the application of wavelet transform to the solution of integral equations for acoustic radiation and scattering

1 IlltroductionIt is well Anown that Boundary Element Method (BEM), based on boundary integralequation, leads the reduction of the dimensionallty of the problem by one because the prob1emis formulated in terms of the flelds on botmdary ouly BEM, hOWver, generates algebraicequations with full matrices, whose solutions are moe eapensive than that of the bandedmatrices of FEM[1'2]. On the other hand, in boundary integral forInulations, an integral operatorhas the global behavior, that can b…     

Continuous transformation from quasicrystals to approximants in Al–Cu–Fe alloys

Continuous transformation of icosahedral quasicrystals as observed in Al-Cu-Fe alloys proceeds through intermediate modulated structures towards rational approximants with a rhombohedral structure. Corresponding to the diffuse scattering in the electron diffraction during the transformation, a tweed contrast emerges throughout the icosahedral phase matrix. High-resolution electron microscopy reveals a complex modulated structure which tends to evolve into rhombohedral microdomains. The observed distortion of the reciprocal quasilattice due to the structural modulation has been simulated on a computer by introducing linear phason strains into the quasicrystals.     

Evanescent wave scattering by aggregates of clusters – application to optical near-field microscopy

Extended Mie-theory is used to investigate scattering and extinction of evanescent waves by aggregates of clusters. In an application to apertureless near-field optical microscopy involving total internal reflection at the surface substrate–air, the variation of the scattered power is calculated when a silicon particle is scanned across single clusters or aggregates of clusters in the evanescent field. Metallic, dielectric, and semiconducting particles are taken into consideration, and the dependence on sizes, materials, and the wavelength is discussed. Received: 27 August 1999 / Revised version: 8 November 1999 / Published online: 1 March 2000     

Phase coexistence and interface structure of a two-component Lennard-Jones fluid in porous media: application of Born—Green—Yvon equation

The Born-Green-Yvon equation with smoothed density approximation is used to calculate the liquid-liquid density profiles of a symmetric Lennard-Jones fluid in a hard sphere disordered matrix. The phase diagrams are evaluated for model systems characterized by different matrix densities and compared with the results of theoretical predictions and the Monte Carlo simulations of Gordon, P. A., and Glandt, E. D., 1996, J. chem. Phys., 105, 4257. It was found that increasing the matrix packing fraction reduces the magnitude of the miscibility gap and smooths the density profiles between two coexisting phases.     

An application of radiation boundary condition to scattering problem of acoustic waves in fluids

A numerical method of solving acoustic wave scattering pnblemin fluids is described.Radiation boundary condition(RBC)obtained byfactorization method of Helmholtz equation is applied to transforming theexterior boundary value problem in unbounded region into one in a finiteregion.Combined with RBC and scatterer surface boundary condition,Helmholtz equation is solved numerically by the finite difference method.Computational results for sphere and prolate spheroidal scatterers are inexcellent agreement with eigenfunction solutions and much better than theresults of OSRC method.     

Time-resolved spectral characteristics of external-cavity quantum cascade lasers and their application to stand-off detection of explosives

We present the time-resolved spectral analysis of the settling process in a pulsed external-cavity quantum-cascade laser (EC-QC laser) emitting in the wavelength range around 7.4 μm. Due to mode competition between the two cavities formed by the laser-chip on one hand and the external-cavity on the other hand, a time-dependent spectral emission on a ns time-scale can be observed. Depending on the spectral characteristic of the external cavity with respect to the chip gain curve time-delays of the external cavity emission of 15–35 ns within the 100 ns drive pulse can be observed.     

Mössbauer and VNIR study of dust generated from olivine basalt: application to Mars

Mössbauer spectroscopy of surface rocks, soil, and dust on Mars from the Mars Exploration Rovers (MER) suggests that the mineral olivine is widespread on the surface. Detection of the mineral by near-IR optical spectroscopy from Martian orbit indicates that it is found in relatively small isolated outcrops concentrated in the floors and rims of craters distributed around the ancient cratered highlands of Mars. To shed light on this apparent paradox, we have performed a detailed Mössbauer and visible-near-IR (VNIR) investigation of dust generated from Icelandic olivine basalt, which is a good Mössbauer analogue to the igneous rocks at Gusev crater on Mars. The results show that the amount of olivine relative to pyroxene can be underestimated by almost an order of a magnitude in VNIR reflectance spectra, most probably because of the longer effective optical path length in pyroxene compared to olivine.     

The pion–nucleon scattering lengths from pionic hydrogen and deuterium

This is the final publication of the ETH Zurich–Neuchatel–PSI collaboration on the pionic hydrogen and deuterium precision X-ray experiments. We describe the recent hydrogen 3p–1s measurement, report on the determination of the Doppler effect correction to the transition line width, analyze the deuterium shift measurement and discuss implications of the combined hydrogen and deuterium results. From the pionic hydrogen 3p–1s transition experiments we obtain the strong-interaction energy level shift eV and the total decay width eV of the state. Taking into account the electromagnetic corrections we find the hadronic s-wave scattering amplitude for elastic scattering and for single charge exchange, respectively. We then combine the pionic hydrogen results with the 1s level shift measurement on pionic deuterium and test isospin symmetry of the strong interaction: our data are still compatible with isospin symmetry. The isoscalar and isovector scattering lengths (within the framework of isospin symmetry) are found to be and , respectively. Using the GMO sum rule, we obtain from a new value of the coupling constant () from which follows the Goldberger–Treiman discrepancy . The new values of and imply an increase of the nucleon sigma term by at least 9 MeV. Received: 20 April 2001 / Revised version: 6 July 2001 / Published online: 24 August 2001     

Semi-adiabatic Shinnar–Le Roux pulses and their application to diffusion tensor imaging of humans at 7T

The adiabatic Shinnar–Le Roux (SLR) algorithm for radiofrequency (RF) pulse design enables systematic control of pulse parameters such as bandwidth, RF energy distribution and duration. Some applications, such as diffusion-weighted imaging (DWI) at high magnetic fields, would benefit from RF pulses that can provide greater B₁ insensitivity while adhering to echo time and specific absorption rate (SAR) limits. In this study, the adiabatic SLR algorithm was employed to generate 6-ms and 4-ms 180° semi-adiabatic RF pulses which were used to replace the refocusing pulses in a twice-refocused spin echo (TRSE) diffusion-weighted echo planar imaging (DW-EPI) sequence to create two versions of a twice-refocused adiabatic spin echo (TRASE) sequence. The two versions were designed for different trade-offs between adiabaticity and echo time. Since a pair of identical refocusing pulses is applied, the quadratic phase imposed by the first is unwound by the second, preserving the linear phase created by the excitation pulse. In vivo images of the human brain obtained at 7 Testa (7 T) demonstrate that both versions of the TRASE sequence developed in this study achieve more homogeneous signal in the diffusion-weighted images than the conventional TRSE sequence. Semi-adiabatic SLR pulses offer a more B₁-insensitive solution for diffusion preparation at 7 T, while operating within SAR constraints. This method may be coupled with any EPI readout trajectory and parallel imaging scheme to provide more uniform coverage for diffusion tensor imaging at 7 T and 3 T.     

Covariant hysteretic constitutive theory for Maxwell’s equations: application to axially rotating media

This paper explores a class of non-linear constitutive relations for materials with memory in the framework of covariant macroscopic Maxwell theory. Based on earlier models for the response of hysteretic ferromagnetic materials to prescribed slowly varying magnetic background fields, generalized models are explored that are applicable to accelerating hysteretic magneto-electric substances coupled self-consistently to Maxwell fields. Using a parameterized model consistent with experimental data for a particular material that exhibits purely ferroelectric hysteresis when at rest in a slowly varying electric field, a constitutive model is constructed that permits a numerical analysis of its response to a driven harmonic electromagnetic field in a rectangular cavity. This response is then contrasted with its predicted response when set in uniform rotary motion in the cavity.     

Some experimental results on the angular intensity distributions of backscattering and transmission from an isotropic P32 β source on thick and thin plane scattering media

The P³² saturation backscattering component, named side scattering bySeliger, is verified and further investigated for thin Al foils in connection with transmission, by means of a simple small solid angle Geiger counter method. Variations occurring in the side scattering angular distribution, due to surface effects, are illustrated and can explain some errors in absolute beta counting, and are related to results reported byKanter.     

Polarization spectra of Rb atoms and their application in laser frequency stabilization

Polarization spectra of rubidium atoms were investigated with different uncrossed angles between the polarizer and the analyzer. The variation of the spectra was derived theoretically as a function of arbitrary angle, and measured experimentally for different angles. The spectral profile of D2 line of rubidium was further used to stabilize the frequency of a diode laser. It was demonstrated that the laser linewidth was reduced to 2 MHz.     

Characteristics of holographic scattering and its application in determining kinetic parameters in PQ-PMMA photopolymer

This paper characterizes holographic scattering and demonstrates its application in determining the kinetic parameters in materials with high transmittance and strong holographic scattering like phenanthrenequinone doped poly (methyl methacrylate) (PQ-PMMA). We define a polymerization rate parameter which can be determined by the temporal evolution of the scattering losses. Two basic kinetic parameters, quantum yield and molar-absorption coefficient, are obtained by nonlinear fitting the curve of the polymerization rate parameter as a function of the thickness, which are 1.9×10⁻⁶ mol/einstein and 2.1×10⁴ cm²/mol for a wavelength of 532 nm respectively. These results improve the understanding of photochemical behaviors and allow us to describe the grating formation in the photopolymer reasonably.     

Anisotropic diffusion in media with absorbing traps (application to the Keller–Dykhne theorem)

Anisotropic diffusion in multidimensional media with absorbing traps is investigated. It is shown that the diffusion asymptotic forms of the survival probability over long time intervals are determined by a new effective diffusion coefficient. Exact expressions derived for the effective diffusion coefficient generalize the well-known Dykhne–Keller 2D results to the 3D case. In other words, the dynamic diffusion approach is used for obtaining a generalization of the Dykhne–Keller theorem to the 3D case.     

Theory of decoherence due to scattering events and Lévy processes

A general connection between the characteristic function of a Lévy process and loss of coherence of the statistical operator describing the center of mass degrees of freedom of a quantum system interacting through momentum transfer events with an environment is established. The relationship with microphysical models and recent experiments is considered, focusing on the recently observed transition between a dynamics described by a compound Poisson process and a Gaussian process.