Size effects on polaritons in thin crystals with perfect interference spectra

Size effects on polaritons in thin plane parallel CdS and CdSe crystals are discussed. For samples not thinner than 0.1 μm the measurements of transmittance and reflectance show the size quantization of the mechanical exciton dispersion and a shift of the resonance frequency of the exciton to the high-energy side with decreasing thickness. However no evidence for the alteration of the oscillator strength or other parameters has been obtained. This conclusion is in conflict with the recently published data taken on CdS samples. The stability of the polariton dispersion in our case is supported by the theoretical study of reflectance ignoring the effects of the finiteness of the exciton radius.     

Electron transition in intercalated disulfide CuCrS<Subscript>2</Subscript>

Electrical, resonant, and magnetic properties of intercalated copper chromium disulfide CuCrS₂ are studied. It is established that CuCrS₂ is an antiferromagnetic semiconductor with Néel temperature T_N=40.7 K and an effective magnetic moment of 4.3µ_B. Anomalies in the electrical, magnetic, and resonant properties of CuCrS₂ are found at T_c=110 K, which suggest an electron transition accompanied by alteration of the valences of the 3d-metal ions.     

Concentration dependence of the viscosity of <Emphasis Type="Italic">tert</Emphasis>-butanol-water mixtures: Physical experiment and computer simulation

The concentration dependence of the viscosity of tert-butanol-water mixtures in the range of tert-butanol mole fractions from 0 to 0.02 was studied experimentally and by computer simulation. The methods of potentials of mean force and statistical geometry were successfully applied to analysis of physical factors responsible for the extrema in the composition-property dependences. The maximum in the concentration dependence of the viscosity is due to association of solvent molecules.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1250–1256.Original Russian Text Copyright © 2004 by Lukyanchikova, Ivlev, Kiselev, Alper.This revised version was published online in April 2005 with a corrected cover date.     

Effect of Elevated External Pressure on the Rate of the Diels-Alder Reaction of 9-Methylanthracene with Acrylonitrile,Catalyzed by Gallium Chloride

External pressure was found to similarly affect the rate of a gallium chloride-catalyzed Diels-Alder reaction between 9-methylanthracene with acrylonitrile and a noncatalyzed reaction of 9,10-dimethylanthracene with acrylonitrile. The observation of equal activation volumes is consistent with the assumption that elevated pressure very weakly affects the bond energy in the n, complex of acrylonitrile with gallium chloride.     

Modulated replica symmetry breaking schemes for antiferrimagnetic spin glasses

We define modulated replica symmetry breaking (RSB) schemes which combine tree- and wave-like structures. A modulated scheme and unmodulated RSB are evaluated at 1-step level for a semiconductor model with antiferromagnetic Korenblit-Shender interaction. By comparison of the free energies we find evidence that a T = 0 phase transition in the ferrimagnetic phase leads to a transition between the different RSB-schemes. An embedding factor of Parisi block matrices with sublattice-asymmetrical size is employed as a new variational parameter in the modulated scheme.Received: 11 December 2003, Published online: 15 March 2004PACS: 68.35.Rh Phase transitions and critical phenomena - 75.10.Nr Spin glass and other random models     

Isotopic shifts and the hyperfine structure of the samarium spectral lines at 672 and 686 nm

Spectra of saturated absorption of Sm atomic vapor from the ground state ⁷ F ₀ and the first even metastable level ⁷ F ₁, ε′=292.58 cm^?1 of the 4f ⁶6s ² configuration to the odd level 4_f ⁶(⁷ F)6s6p(³ P ^o)⁹ F ₁ ^o , ε,=14863.85 cm^?1 were recorded. The lines of the isotopic series were identified, and the hyperfine structure of lines in the spectra of isotopes with a nonzero nuclear spin was determined. The relative isotopic shifts and the hyperfine splitting of the even level 4f ⁶6s ²(⁷ F ₁) were determined.     

Peculiarities of pulsed ion implantation from a laser plasma containing multiply charged ions

A mathematical model describing the dynamics of a pulsed laser plasma with multiply charged ions, as well as the formation of the accelerated ion flow in an external magnetic field, is developed. Experimental studies and mathematical simulation by the particle-in-cell method are used to determine the role of multiply charged ions in the process of ion implantation into a silicon substrate from the pulsed plasma containing singly and doubly charged titanium ions. The plasma spreads between parallel-plate electrodes (Ti target and Si substrate) along the normal to the surface of the target. Ions are accelerated by high-voltage negative pulses applied to the substrate. It is found that doubly charged ions effectively participate in the implantation process when an external electric field is applied very soon after the laser action on the target. The application of a high-voltage pulse with an amplitude of 50 kV 0.5 μs after a laser pulse leads to ion implantation with an energy close to 100 keV. With increasing delay in the application of the high-voltage pulse, the upper boundary of the energy spectrum of implanted ions is displaced towards lower energies. Comparison of the depth profiles of titanium distribution in silicon calculated from the results of simulation are compared with the experimental profiles shows that the model developed here correctly describes the formation of the high-energy component of the ion flow, which is responsible for defect formation and doping of deep layers of the substrate.