激光三角法位移测量中被测物面倾斜产生测量误差的机理及其校正

利用光散射原理对激光三角法测位移中被测物的物面倾斜产生测量误差的机理进行理论研究。推得了面倾斜与相应的倾斜误差的关系式。实验结果与理论预计基本一致。在此基础上提出了校正倾斜误差的方法，并用模拟实验验证了该方法的可行性。     

Johann单色器能量分辨率分析

Johann单色器是一种广泛应用的X光单色器,对其能量分辨率已有若干工作进行过分析.对此问题进行了进一步的分析,改进了已有的工作.将计算结果和已有公式的计算结果同时与SHADOW追迹结果进行比较,理论计算与追迹结果有更好地吻合,同时适用范围更大.     

First-order magnetic phase transitions in thin films

Using the simple Landau model, we discuss near-surface magnetic effects for thin films corresponding to first-order phase transitions. The size effects observed in ultrathin ferroelectric films are in agreement with this theoretical interpretation. The presence of a weak external field is also formulated. The text was submitted by the authors in English.     

A Comparison of the Experimental and ab Initio Values of theO NMR Chemical Shifts in the Carbonyl Group

New experimental and theoretical results are presented for the NMR shielding of oxygen in the carbonyl group. The experimental values clearly demonstrate that the solvent effects are very significant. The new results for the chemical shifts are in better agreement than the previous literature data with the corresponding ab initio values calculated for isolated molecules.     

光折变晶体(BaSr)TiO3感应自泵浦相位共轭及光学双稳的理论分析

给出光折变晶体感应自泵浦相位共轭的一种理论解释，利用数值计算求解相应的耦合波方程，得出感应自泵浦相位共轭光与诱导光之间在一定条件下所呈现的双稳关系以及可逆尖和不可逆感应的特性，其分析结构与笔者先前得到的实验结果吻合。     

Waveguides in three-dimensional photonic-bandgap materials by direct laser writing and silicon double inversion

Three-dimensional complete photonic-bandgap materials offer unique opportunities regarding the integration of optical waveguide architectures in three dimensions. However, corresponding experimental realizations are truly sparse. Here, we fabricate such waveguides using direct laser writing and a silicon double-inversion procedure. The optical characterization is in good agreement with theoretical calculations, raising hopes that even more complex architectures may soon come into reach.     

Oscillations quantiques des coefficients de pouvoir thermoelectrique et de conductivite thermique: theorie et mesures dans Cd3As2

Quantum oscillations have been observed in the thermoelectric power and thermal conductivity coefficients of a semiconductor Cd₃As₂ single crystal. Theoretical expressions for these coefficients, taking into account the Landau level broadening, are derived in this paper. The good agreement found between the thermoelectric power measurements and the corresponding theoretical expressions for the temperature and magnetic field dependence of the quantum oscillation amplitudes and the absolute values of the amplitudes has allowed us to calculate effective mass values which are in agreement with Shubnikov-de Haas measurements.     

Mean single-particle potentials and single-particle energies in a microscopic model of the nucleus

A method for calculating mean single-particle potentials and the corresponding single-particle energy levels in nuclei is presented. Specific formulas for these quantities are written for Slater determinant wave functions in the case of polarized orbitals and a central exchange nucleon-nucleon potential featuring a Gaussian radial dependence. The resulting theoretical estimates of single-particle properties of the nuclei considered in the present study are in satisfactory agreement with relevant experimental data.     

Nonlinear dielectric effect of dipolar fluid mixtures

The linear and nonlinear dielectric effect for two- and three-component dipolar fluid mixtures are studied within the framework of the mean spherical approximation (MSA) of dipolar hard sphere mixtures. In our approach, equally sized dipolar hard spheres with different dipole moments are considered. Based on earlier results for the electric field dependence of the polarization our analytical equations show the so-called normal saturation effects, which are in good agreement with corresponding canonical ensemble Monte Carlo simulation data. Comparisons between the MSA based theoretical results and the corresponding Langevin and Debye-Weiss theories are also made.     

Perpendicular magnetocrystalline anisotropy in tetragonally distorted Fe-Co alloys

We report on the experimental realization of tetragonal Fe-Co alloys as a constituent of Fe0.36Co0.64/Pt superlattices with huge perpendicular magnetocrystalline anisotropy energy, reaching 210 microeV/atom, and a saturation magnetization of 2.5 microB/atom at 40 K, in qualitative agreement with theoretical predictions. At room temperature the corresponding values and are achieved. This suggests that Fe-Co alloys with carefully chosen combinations of composition and distortion are good candidates for high-density perpendicular storage materials.     

Imaging the local density of states of optical corrals

This paper reports the experimental observation, at optical frequencies, of the electromagnetic local density of states established by nanostructures corresponding to the recently introduced concept of optical corral [G. Colas des Francs et al., Phys. Rev. Lett. 86, 4950 (2001)]. The images obtained by a scanning near-field optical microscope under specific operational conditions are found in agreement with the theoretical maps of the optical local density of states. A clear functionality of detection by the scanning near-field optical microscope is thereby identified since the theoretical maps are computed without including any specific tip model.     

Stress dependence of electron-hole liquid parameters in silicon

The electron-hole liquid recombination luminescence in silicon is studied as a function of stress up to corresponding valence band splittings of 30 meV for <100>- and <111>-stress directions. EHL densities and exchange-correlation energies as obtained from lineshape fits are in general agreement with recent theoretical data. Systematic deviations in detail, however, indicate that - contrary to simplifying theoretical assumptions - a band structure dependence of the exchange and correlation energy E_xc has to be taken into account.     

Electron ionization cross sections for neutral fullerene C70

The energy dependent ionization cross sections corresponding to the formation of singly, doubly and triply charged cations in the electron impact ionization of C₇₀ are evaluated employing a semiempirical formulation at the incident electron energies of 100 and 200 eV. The integral ionization cross sections have also been calculated in the energy range varying from ionization thresholds to 1000 eV which revealed a satisfactory agreement with the available experimental and the theoretical data. The ionization rate coefficients corresponding to the various cations have also been evaluated using the presently calculated ionization cross sections and Maxwell-Boltzmann energy distributions.     

Flexural resonance vibrations of piezoelectric ceramic tubes in Besocke-style scanners

Flexural resonance vibrations of piezoelectric ceramic tubes in Besocke-style scanners with nanometer resolution are studied by using an electro-mechanical coupling Timoshenko beam model.Meanwhile,the effects of friction,the first moment,and moment of inertia induced by mass loads are considered.The predicted resonance frequencies of the ceramic tubes are sensitive to not only the mechanical parameters of the scanners,but also the friction acting on the attached shaking ball and corresponding bending moment on the tubes.The theoretical results are in excellent agreement with the related experimental measurements.This model and corresponding results are applicable for optimizing the structures and performances of the scanners.     

Theoretical analysis of spin-resolved photoemission data from ferromagnetic Fe(001)

To interpret recent spin-, energy- and angle-resolved experimental photoemission spectra at photon energies ranging from 20 to 70 eV, one-step calculations on the basis of a non-relativistic Green function formalism have been performed together with a calculation of the corresponding bulk band structure and momentum-resolved layer-by-layer quasi-particle density of states. The theoretical spectra are in good agreement with the data. Individual features are explained in terms of bulk interband transitions and emission from a majority-spin surface resonance. Self-energy corrections are found to be important and in qualitative disagreement with recent microscopic theory.     

Highly stretched single polymers: atomic-force-microscope experiments versus ab-initio theory

Experimental single-molecule stretching curves for three backbone architectures (single-stranded DNA, various types of peptides, polyvinylamine) are quantitatively compared with corresponding quantum-chemical (zero-temperature) ab-initio calculations in the high-force range of up to two nanonewtons. For high forces, quantitative agreement is obtained with the contour length of the polymers as the only fitting parameter. For smaller forces, the effects of chain fluctuations are accounted for by using recent theoretical results for the stretching response of a freely-rotating-chain model.     

液体表面低频声波的非线性声光效应

实现了液体表面上低频声波的光衍射,得到了稳定的、具有高阶衍射的高反衬衍射图样.理论上首次考虑到表面声波中的高次谐波,得到了相应的非线性条件下衍射强度分布的解析表达式,并将这种非线性理论与实验结果进行对比.对比结果表明,非线性理论与实验结果有更高的吻合程度.     

Nonlinear transport of Bose--Einstein condensates in a double barrier potential

The stable nonlinear transport of the Bose-Einstein condensates through a double barrier potential in a waveguide is studied. By using the direct perturbation method we have obtained a perturbed solution of Cross-Pitaevskii equation. Theoretical analysis reveals that this perturbed solution is a stable periodic solution, which shows that the transport of Bose-Einstein condensed atoms in this system is a stable nonlinear transport. The corresponding numerical results are in good agreement with the theoretical analytical results.     

Copper(II) and nickel(II) complexes of tetradentate Schiff base ligand: UV-Vis and FT-IR spectra and DFT calculation of electronic,vibrational and nonlinear optical properties

The experimental fourier transform infrared (FT-IR) and ultraviolet-visible (UV-Vis) spectra of copper(II) and nickel(II) complexes of the deprotonated tetradentate Schiff base ligand N,N′-bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine (H₂L) are compared with their corresponding theoretical ones. The applied theoretical method is based on the density functional theory and time-dependent density functional theory at the UPBE0/PBE0 levels using Def2-TZVP basis set. The computational optimised geometric parameters of the complexes are in good agreement with their corresponding experimental data. The FT-IR and UV-Vis spectra of the complexes were reproduced on the basis of their optimised structures. The vibrational assignments of some fundamental modes of the complexes are performed. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies are calculated. The analyses of the calculated electronic absorption spectra of the complexes are carried out to elucidate the electronic transitions assignments and their characters. Second-order nonlinear optical property of the complexes is evaluated by the above-mentioned theoretical method that implies much greater values for the complexes in comparison with the corresponding value of urea.     

Spectroscopic strengths for 6Li-induced alpha-particle transfers on 24Mg

²⁴Mg(⁶Li, d) angular distributions for transitions to low-lying states in ²⁸Si are well fitted by exact finite-range DWBA calculations and yield relative spectroscopic strengths in good agreement with theoretical predictions as well as with the corresponding results from other α-particle transfer reactions.