A monopole mass filter with a hyperbolic V-shaped electrode

In this article we compare the classical monopole mass filter of von Zahn and the monopole mass filter with a hyperbolic V-shaped electrode. The experimental results and those of computer simulation for both mass spectrometers are presented. We show that the replacement of a conventional 90 degrees V-shaped electrode by an electrode with a hyperbolic profile substantially improves the peak shape of any given mass, and increases the mass resolution by a factor of 3-4 and the abundance sensitivity by a factor of 100. The potential of high analytical performance combined with electroforming techniques for electrode manufacture indicate future practical uses of such instruments. Copyright 1999 John Wiley & Sons, Ltd.     

Advances of laser refrigeration in solids

The physics of laser cooling in solids is discussed. The coherent optical cooling of dye-doped polymer films in regime of anti-Stokes femtosecond photon echo is analyzed. The possibility of improved optical cooling by doped nanocrystalline structures is studied.     

Anti-Stokes femtosecond photon echo in dye-doped polymer films and the possibility of coherent optical cooling

An anti-Stokes model is proposed to explain the known experimental data on the femtosecond photon echo in dye-doped polymer films at room temperature. The possibility of implementing the anti-Stokes mode of coherent laser cooling of such films is analyzed.     

Prospects for the optical cooling of CdS nanocomposites

The possibility of using CdS nanocomposites for optical cooling is analyzed on the basis of their spectroscopic properties. The physical principles of laser cooling in semiconductor structures are discussed.     

Influence of Cr<Superscript>+</Superscript> ion implantation and pulsed ion-beam annealing on the formation and optical properties of Si/CrSi<Subscript>2</Subscript>/Si(111) heterostructures

The effect of pulsed ion-beam annealing on the surface morphology, structure, and composition of single-crystal Si(111) wafers implanted by chromium ions with a dose varying from 6 × 10¹⁵ to 6 × 10¹⁶ cm⁻² and on subsequent growth of silicon is investigated for the first time. It is found that pulsed ion-beam annealing causes chromium atom redistribution in the surface layer of the silicon and precipitation of the polycrystalline chromium disilicide (CrSi₂) phase. It is shown that the ultrahigh-vacuum cleaning of the silicon wafers at 850°C upon implantation and pulsed ion-beam annealing provides an atomically clean surface with a developed relief. The growth of silicon by molecular beam epitaxy generates oriented 3D silicon islands, which coalesce at a layer thickness of 100 nm and an implantation dose of 10¹⁶ cm⁻². At higher implantation doses, the silicon layer grows polycrystalline. As follows from Raman scattering data and optical reflectance spectroscopy data, semiconducting CrSi₂ precipitates arise inside the silicon substrate, which diffuse toward its surface during growth.     

On the quantum theory of superradiance in two-and three-level macroscopic systems

Modified quantum kinetic equations for the superradiance in two-and three-level macroscopic systems that interact with electromagnetic fields are derived based on the method for elimination of the boson variables. It is demonstrated that the theoretical predictions are in good agreement with the experimental data.     

Femtosecond photon echo in a dye-doped polymer film and the possibility of coherent optical cooling

The signals of primary and stimulated femtosecond photon echoes are investigated in a dye-doped polymer film at room temperature. The homogeneous S ₀ → S ₁ spectral line width, which is due to the interaction between the impurity molecules and the quasi-local low-frequency modes, is estimated (≈5 × 10¹² Hz). Special attention is paid to the study of spectra of femtosecond echo signals. The short-wave shifts of these spectra, with respect to the spectrum of femtosecond exciting pulses, are observed. These shifts indicate that the anti-Stokes regime of femtosecond pulse emission is realized. Therefore, the coherent regime of laser cooling of solids appears to be possible. The prospects of using of this new cooling regime in the function of a solid-state optical refrigerator are discussed.     

Justification of the Kirchhoff hypotheses and error estimation for two-dimensional models of anisotropic and inhomogeneous plates, including laminated plates

Asymptotic analysis of the problem describing deformation ofa thin cylindrical plate with clamped lateral side is performed.The problem is considered under the most general statement withthe plate being laminated and consisting of an arbitrary numberof nonhomogeneous and anisotropic (21 elastic moduli) layers.Explicit integral representations of the differential operatorswhich form the two-dimensional model of the plate are derived.In the case when the elastic moduli of each of the layers areconstant, these integral representations turn into algebraicones. The asymptotic procedure is justified with the help ofa weighted inequality of Korn's type. The error estimates obtainedgive a rigorous mathematical proof of both of Kirchhoff's hypotheses(kinematic and static) and shed light on the well-known intrinsicinconsistency of two of the hypotheses.