Experimental observation of quantum corrections to electrical resistivity in nanocrystalline soft magnetic alloys

X-ray diffraction patterns of nanocrystalline Fe-Cu-Nb-Si-B (FINEMET) alloys reveal that bcc α-Fe/α-FeSi crystallites with the average grain size of 20(5) nm are dispersed in amorphous matrix. Enhanced electron—electron interaction (EEI) and quantum interference (QI) effects as well as electron-magnon (and/or electron-spin fluctuation) scattering turn out to be the main mechanisms that govern the temperature dependence of resistivity. Of all the inelastic scattering processes, inelastic electron-phonon scattering is the most effective mechanism to destroy phase coherence of electron wave functions. The diffusion constant, density of states at the Fermi level and the inelastic scattering time have been estimated, for the first time, for the alloys in question Article presented at the International Symposium on Advances in Superconductivity and Magnetism: Materials, Mechanisms and Devices, ASMM2D-2001, 25–28 September 2001, Mangalore, India.     

Mathematical Modeling of Multilayer Filters for Telecommunication

The article presents an interactive approach to the design of Wavelength Division Multiplexing (WDM) filters that combines classical design methods for multi-resonator systems with a semi-heuristic integer optimization method. This approach proves to be exceptionally efficient from the computational point of view and generates a whole range of different filter designs with virtually equivalent spectral properties. The article also considers a method for analyzing the sensitivity of WDM filters to manufacturing errors. The sensitivity analysis relies on computer simulation of thin-layer coating with optical monitoring of layer thickness by the turning point method. This analysis enables the designer to assess alternative filter designs with the purpose of improving manufacturing efficiency.     

CdSe和ZnO量子点的拉曼光谱研究

本文介绍了用拉曼光谱研究CdSe和ZnO两种Ⅱ Ⅳ族量子点材料的结果,对拉曼峰进行了指认。观察到的光学声子峰位的移动被认为是由量子限制效应引起。     

Analysis of tunable diode-laser spectra of Q(J,0) lines in CH3F near 1475 cm using a multispectrum fitting technique

We have analyzed the methyl fluoride ^RQ(J,0)Q branch lines located near 1475 cm⁻¹ using a simultaneous multi-spectrum fitting technique. In this analysis we have used previously recorded diode-laser data in which we collected many data points covering only one or two Q branch lines in a particular run. The analysis consists of simultaneously fitting 57 spectra collected with numerous pressure and path length conditions for all absorption lines. The data are concatenated to create one continuous spectrum of the Q branch. We have determined the intensity and self-broadened widths at 296 K for 23 ^RQ(J,0) lines.     

Matrix perturbation theory for driven three‐level systems with damping

We investigate the dynamics of the Λ system driven by two resonant laser fields in presence of dissipation for coupling strengths where the rotating‐wave approximation starts to break down. This regime is characterised by Rabi frequencies being approximately equal or smaller than the field frequencies. A systematic procedure to obtain an expansion for the solution of the Bloch evolution equations of the system is presented. The lowest contribution results to be the well‐known rotating‐wave approximation. The method is based on a semi‐classical treatment of the problem, and its predictions are interpreted fully quantum mechanically. The theory is illustrated by a detailed study of the disappearance of coherent population trapping as the intensities of the fields increase.     

Destruction of a solid film under the action of ultrashort laser pulse

Molecular-dynamics (MD) simulation of the destruction of a crystal film heated by a femtosecond laser pulse was carried out. Heating is assumed to be instantaneous, because there is no time for the material to be displaced during the pulse. Film destruction is caused by the interaction of unloading waves. It can be considered as a model of a more complex process of splitting out of a thin surface layer from a massive target in the case where the layer remains solid after heating. It was found that the crystal order is broken due to the stretching strains and to the strong anisotropy of residual stress, resulting in a bipartition of the layer separating from the target. The lattice stretching and the formation of anisotropic stresses are due to the expansion of a heated lattice.     

Some necessary and sufficient conditions for Hypercyclicity Criterion

We give necessary and sufficient conditions for an operator on a separable Hilbert space to satisfy the hypercyclicity criterion. This paper is a part of the second author’s Doctoral thesis, written at Shiraz University under the direction of the first author.     

Investigation of organic impurities adsorbed on and incorporated into electroplated copper layers

At room temperature electroplated copper layers exhibit changes in resistivity, residual stress, and microstructure. This process, known as self-annealing, is intimately linked to the release of organic impurities, which stem from the incorporation of organic additives into the Cu layer in the course of the electroplating process. The behavior of these impurities during self-annealing, represented by the carbon content, could be detected by analytical radio frequency glow discharge optical emission spectrometry (GD-OES) and carrier gas hot extraction (CGHE). The precondition of a quantitative determination is a surface cleaning procedure to remove adsorbed organics from the copper surface. It was observed that at first almost all impurities have to leave the Cu metallization before an accelerated abnormal grain growth can start. The small amount of remaining organic species after self-annealing could be quantified by both examination techniques, GD-OES and CGHE.