Spectral characteristics of subcritical carbon dioxide in nanopores

Coherent anti-Stokes Raman scattering spectra measured within the Q-branch of the vibrational transition ν₁ are used to gain insights into the state of carbon dioxide molecules in nanopores of Vycor™ glass at room temperature (20.5°C) and a subcritical temperature of 30.5°C and gas pressures up to the saturation point P _sat for each temperature. Along with the main spectral component, belonging to gaseous CO₂ molecules, the spectra recorded at pressures close to P _sat feature a second (low-frequency) component. The second component is associated with the contribution from the CO₂ molecules trapped inside pores. A spectral deconvolution with account for the interference of these two bands makes it possible to estimate the spectral characteristics of the second (low-frequency) component at each temperature. At 20.5°C, the bandwidth of the low-frequency component decreases with CO₂ pressure, a behavior that can be explained by the transition of CO₂ from the adsorbed to the condensed state in the pore. At the subcritical temperature of 30.5°C, the spectral width of the second component is pressure-independent and close to the value measured in the bulk of the supercritical fluid, a result likely associated with a low-temperature shift of the critical point of the substance trapped in nanopores.     

Features of Photoluminescence of Double Acceptors in HgTe/CdHgTe Heterostructures with Quantum Wells in a Terahertz Range

JETP Letters - The terahertz photoluminescence spectra of HgTe/CdHgTe heterostructure with quantum wells under interband optical excitation with a power of 3 to 300 mW have been studied in the...     

Energy transfer studies in krypton-xenon mixtures excited in a cooled DC discharge

The VUV spectrum of gaseous mixtures of krypton with a small amount of xenon added was investigated in the range 115-200 nm. The mixtures were excited in a capillary DC discharge where the capillary could be cooled by using liquid nitrogen. The mixed molecule band around the XeI resonance line at nm and the mixed molecule continuum to the long wavelength side from the line were analysed. The band around nm was identified as transitions between a weakly bound excited state and the weakly bound ground state of XeKr molecules. When cooling the capillary wall, the appearance of the Xe₂ continuum was observed. The effect is ascribed to energy transfer between molecular states as a consequence of radiation trapping in the band around nm. The role of the mixed molecule in the formation of the VUV spectrum of the gas mixture is discussed and underlined. Received 12 May 1999 and Received in final form 27 August 1999     

On the relaxation of a medium after excitation with single fast heavy ions

A plasma model of relaxation of a medium in heavy-ion tracks in condensed matter has been proposed. The model is based on the solution of time-dependent equations of radiative-collisional kinetics. The state of the medium, which is described in the framework of the classical model of multiple ionization of target atoms by a field of fast multiply charged ions, is used as the initial condition. The relaxation in the plasma is investigated using molecular dynamics simulation. An analysis of the results of the calculations performed has made it possible to determine the range of material parameters at which the plasma model actually changes over to the atomic model and to establish the conditions where the atomic model is a very rough approximation. It is demonstrated that the plasma model adequately describes the X-ray spectra recorded upon interaction of ion beams with condensed targets. An X-ray spectral method based on the plasma model is proposed for diagnosing the plasma in fast-ion tracks. The results obtained can be useful in examining the initial stage of defect formation in solids under irradiation with single fast heavy ions.     

Polarization experiments with the SPIN setup at the ITEP synchrotron

New experimental data on the spin-rotation parameters A and R measured for elastic π ^± p scattering in the resonance region and on the asymmetry in pC scattering at primary momenta in the range 1.35–2.02 GeV/c, as well as in quasielastic proton scattering on nuclei in the same momentum range, are summarized. All these data were recently obtained by using the proton synchrotron installed at the Institute of Theoretical and Experimental Physics (ITEP, Moscow). The spectrum and features of seven isospin-3/2 baryon resonances that form a peak in the total cross section at a c.m. energy of 1.9 GeV are analyzed on the basis of new data on the parameters A and R, and the results of this analysis are presented. The experiments surveyed in this article were performed by a collaboration of researchers from ITEP and the Petersburg Nuclear Physics Institute (PNPI, Gatchina), the ITEP-PNPI collaboration.     

57Fe Probe Mössbauer Study of Magnetic Phase Transitions in MnP Phosphide

Journal of Experimental and Theoretical Physics - 57Fe Mössbauer studies of Mn0.99557Fe0.005P monophosphide have been performed in a wide temperature range including magnetic transitions at...     

Holographic Waveguide Periscopes in Augmented Reality Displays

Optics and Spectroscopy - Main properties of holographic waveguide periscopic multiplexors of the exit pupil of optical systems of augmented reality displays are considered. Limitations in the...     

The Effect of a Weak Magnetic Field on the Sensitivity of Powdered Pentaammine (5-Nytrotetrazolato-N2) Cobalt(III) Perchlorate of Various Dispersions to the Effects of a High-Current Electron Beam of Nanosecond Duration

Technical Physics - The results of experiments on the influence of a weak magnetic field on the sensitivity of powdered pentaammine (5-nytrotetrazolato-N2) cobalt(III) perchlorate to a high-current...     

Pressure recovery system for a high-power HF/DF laser: implementation practice

The matter of development of a high-performance pressure recovery system (PRS) for a high-power HF/DF laser is discussed. A sequence of design steps is proposed, which involves estimation of basic characteristics of PRS components with the help of one-dimensional integral and semi-empirical procedures; simulation, to be performed using three-dimensional non-stationary Navier — Stokes equations; experimental modelling aimed at verification of the calculation procedures and at refinement of obtained parameters; and a fullscale experiment. An ejector-type system providing for recovery of pressure from 12 Torr to atmospheric pressure in the gas-dynamic system of an HF/DF laser of several-tens-kilowatt power is developed. Matching conditions for parameters of individual PRS components as well as joint functioning of the PRS with a continuous chemical laser in an integral complex are analysed. Conditions for minimization of mass-dimensional characteristics of the laser-PRS complex necessary for the development of ground-based mobile systems are identified.