Experimental and theoretical study of the far-infrared spectra of HCl dissolved in liquid Ar,Kr, and Xe

New experimental results are reported on the relative absorption intensity distribution in the FIR spectra of HCl dissolved in liquefied Ar, Kr, and Xe at several temperatures along the liquid—vapour coexistence curve. These are treated further by applying a previously developed quantum-statistical spectral theory, which accounts for the line mixing and memory effects. Theoretical spectra are given in terms of the anisotropic potential time autocorrelation functions obtained from classical MD simulations using several empirical analytical potentials with density-adjusted well depths. Globally fair agreement between the theoretical and experimental spectra is demonstrated, except in the high frequency wings, where the theory underestimates the observed intensities. The choice of a particular radial form for the anisotropic HCl/RG potentials is found to be not critical for reproducing the experimental absorption profiles.     

On high energy leptoproduction

The particle distributions and the event structures in high energy leptoproduction are considered in a model where perturbative QCD is used to compute the cross sections to order α _s and the Lund jet model is used for the soft hadronization process. Since complete events are generated by a Monte Carlo program not only single-particle spectra can be studied but also various correlations, thus making a more detailed comparison between theory and experiment possible. The model is found to be in agreement with data from the European Muon Collaboration. We indicate how a one-particle trigger can be used to study an enriched sample of two forward jet events, and exhibit a useful experimental test for the existence of such events with the properties predicted by perturbative QCD. We also indicate how to gain further information on the confinement and soft fragmentation mechanisms.     

Heavy Hadron Spectra to the Order 1/M in Heavy Quark Effective Theory

The heavy meson and baryon spectra are studied to the order of 1/M_Q in heavy quark effective theory. A phenomenological formula for the dependence of the spectra on the isospin and strangeness of the light quark system contained in heavy hadrons is proposed and its predictions are in agreement with the present experimental data. The predictions of beauty hadron masses including the 1/M_Q corrections are given. The parameters of the order of 1/M_Q are estimated from phenomenological analyses.     

Optical transmission of dielectric layers with metallic nanoparticles inhomogeneously distributed over the sample thickness

Dielectric layers with silver nanoparticles in the bulk, synthesized by the vacuum evaporation of metal onto viscous-flow softened polymer substrates are analyzed. New materials with a nonuniform distribution of nanoparticles over the sample thickness are obtained. Optical characteristics of the composition layers are calculated from the transmission spectra. To calculate the optical spectra, a model of a multilayered plane-parallel film structure is considered. Functions of dielectric constants of separate composition layers are determined using the Bruggeman theory of effective medium. A qualitative agreement between the experimental and simulated optical spectra is achieved taking into account nonuniform distribution of metal nanoparticles over the composition material thickness.     

Calculation of the spectra of pseudosound wall-pressure fluctuations in turbulent boundary layers

A simple method is developed for calculating the wall-pressure spectra in turbulent boundary layers. The method is based on the modeling of the wave-number spectrum of the sources that are caused by the interaction of the turbulence-mean shear type. The sources are described in the framework of the semiempirical theory of turbulence. The calculations reveal four characteristic frequency ranges; for these ranges, the specific features of the wall-pressure spectra are determined, and the most general ways of their scaling are found. The calculated spectra and rms values of pressure fluctuations are compared with the experimental data, and a good agreement between the calculations and the experiment is observed.     

EXAFS and Raman study of stoichiometric and oxidized Nd2NiO4+δ

The Ni and the Nd environments in the stoichiometric and oxidized Nd₂NiO_4+δ samples have been investigated using EXAFS spectroscopy. In the stoichiometric compound, the Ni and Nd oxygen coordination numbers have been found to be in good agreement with the neutron diffraction crystallographic data. For the oxidized sample, a rearrangement compatible with an increment of the number of oxygen atoms around the Nd ions is found. This increment is consistent with the location of the excess oxygen atoms between the consecutive neodymium (rare earth) layers. While the Raman spectra of the stoichiometric sample is in accordance with the group theory predictions for a Cmca symmetry, oxidized sample spectra are clearly dominated by the perturbations introduced in the crystal by the oxygen defects.     

Na在Si(111)表面(3×1)有序吸附结构的光电子能谱研究

分析了Si(111)7×7表面上Na(3×1)有序吸附的同步辐射光电子能谱的变化,并与Paggel等的扫描隧道显微镜和光电子能谱比较,得出Na吸附在类余留原子(rest atom)的位置,支持Mnch的模型,与室温下无序吸附Na的光电子能谱相比较,得出Na-Si界面肖特基势垒形成是由Na与Si原子之间的相互作用决定,与表面构形是否有序关系不大,势垒高度与MIGS理论预计值相符。     

Mössbauer spectra of EuPd3B0.5, an experimental test of a microscopic theory

The Mössbauer spectra of EuPd₃B_0.5 have been interpreted on the basis of the general microscopic theory previously developed by the authors. The theory connects the valence state of the europium ion with the distribution of the neighbouring boron atoms. The general characteristics of the present spectra are fairly well accounted for by theory, and an evolution with temperature of the line intensity ratio, in good agreement with the experimental data, is predicted.     

钡原子6p3/2ns自电离里德伯态的研究

用激光多步激发技术研究了处于6p1/2电离限以下的6p3/2ns自电离态的光谱。 并利用最新的R矩阵的计算结果, 结合多通道量子亏损理论进行了理论分析。 理论结果与实验光谱相符合。     

Internal bremsstrahlung accompanying non-unique second-forbidden β-decay of 36Cl

The internal bremsstrahlung spectrum accompanying the non-unique second-forbidden β-decay of ³⁶Cl is measured using the magnetic deflection technique. The true IB spectrum is obtained with the help of the inverse of the detector response matrix. The experimental data in the energy interval 80 to 700 keV are compared with the theoretical spectra of Knipp and Uhlenbeck, and Bloch, Lewis and Ford, and Chang and Falkoff. The agreement between the measurement and theory is not good throughout the energy region of the present investigation, though the experimental points are close to the second-forbidden scalar theory of Chang and Falkoff.     

KLn Dielectronic Recombination Process of B- Through He-like Cu Ions

The KLn dielectronic recombination processes of trapped highly charged B-like through He-like Cu ions are studied theoretically, and the theoretical results are used to analyse our previous experimental data at Heidelberg electron beam ion trap （EBIT）. The theoretical resonant positions agree with the experimental resonant positions to a precision of 0.4%, in comparison with the resonant positions of those highest peaks between theory and experiment. The experimental spectra are then fitted using a formula with the theoretical resonant energies and strengths, the result shows good overall agreement between theory and experiment over a wide electron energy range. The distribution of highly charged states is obtained from the fitting parameters.     

Optical properties of porous silicon

We have measured the absorption spectra and the dispersion of refractive index for porous silicon samples with different porosities in the energy range 1.5–3.5 eV at room temperatures. The experimental data are compared with the dependences calculated by using Bruggeman’s theory for the dielectric constant of a multicomponent system composed of crystal silicon, SiO₂, amorphous silicon, and voids (pores). The best agreement between the experimental and theoretical dependences is achieved for a significant percentage of SiO₂ in the porous silicon samples.     

Theoretical analysis of the MCD spectra of some singlet-triplet transitions in formaldehyde

A recently developed theoretical treatment of the magneto-optical activity of singlet-triplet transitions in molecules which are near-symmetric rotors is employed in simulation of the MCD spectra associated with some singlet-triplet transitions in formaldehyde. The theoretical results are compared with the relevant experimental data, and the agreement between theory and experiment is found to be satisfactory.     

A study of theXVV auger line shape of Fe−Ni alloys

Summary A comparison is performed between theoretical and experimental shapes of theXVV (X=M _2,3 andL ₃) Auger spectra of ferromagnetic Fe _x −Ni_1−x alloys forx=0.48 and 0.27 in order to check if recent theories, which take into account the Coulomb correlation between the two final Auger holes, would be able to reproduce shape and position of the experimental peaks in an accurate way. For the case under investigation, it seems that, at least for the low-energy (M _2,3 VV) spectra and notwithstanding the usual neglecting of matrix element effects, the theory gives results in close agreement with the experimental data. The comparison with the high-energyL ₃ VV spectra is somewhat hampered by an asymmetric broadening of the experimental data on the low kinetic-energy side due to satellite structures, but still gives good agreement on the high kinetic-energy side. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Calculation of prompt fission neutron spectra for 235U(n,f)

The prompt fission neutron spectra for the neutron-induced fission of ²³⁵U at E_n < 5 MeV are calculated using nuclear evaporation theory with a semi-empirical model, in which the nonconstant and constant temperatures related to the Fermi gas model are taken into account. The calculated prompt fission neutron spectra reproduce the experimental data well. For the n(thermal)+²³⁵U reaction, the average nuclear temperature of the fission fragment, and the probability distribution of the nuclear temperature, are discussed and compared with the Los Alamos model. The energy carried away by γ rays emitted from each fragment is also obtained and the results are in good agreement with the existing experimental data.     

相对论夸克模型对重夸克偶素质量谱的研究

介绍了量子场论中基于准势途径的一个相对论夸克模型,并使用这个相对论夸克模型计算了重夸克偶素的质量谱.显示这个相对论夸克模型可较好地拟合实验上肯定的质量谱数据. A relativistic quark model based on the quasipotential approach in quantum field theory is briefly introduced, and by using this model, heavy quarkonium mass spectra are calculated in detail. It is shown that such a model can give results which are in agreement with the observed experimental data on the mass spectra.     

Two-magnon Raman scattering in antiferromagnets at finite temperatures

A high density perturbation method is employed to calculate the two-magnon Raman scattering spectra of antiferromagnets at finite temperatures. The theory incorporates the leading order effects of magnon-magnon interactions, and the results are applied to RbMnF₃ and NiO in the antiferromagnetic phase. A comparison is made with experimental work and fairly good agreement is obtained.     

Momentum resolved bremsstrahlung isochromat spectra from Ni(0 0 1)

Momentum resolved inverse photoemission spectra from Ni(0 0 1) are presented. The experimental dispersion of direct transitions are in good agreement with predictions from a recent band structure calculation and with results from spectra calculated on the basis of a one step theory. Comparison of the present data with earlier normal incidence spectra collected with a different experimental setup reveals a very strong polarization effect.