Experimental study of mode selection in shallow-water sea

The possibilities of matching low-frequency underwater sound pulses to the parameters of an oceanic waveguide are considered. The objective is to optimize the system of few-mode tomographic observation in a shallow-water sea. Experimental data are analyzed for two methods of selecting the low-frequency fewmode pulses propagating in a shallow-water sea. The first method excites probe pulses by vertically elongated arrays, with spatial filtering after vertical or horizontal arrays receive the pulses. The second method is based on exciting broadband signals with linear frequency modulation by a single transmitter. The selection of the few-mode signal is performed by time strobing the signals at the output of the matched filter after a horizontal array receives the pulses. The distance between the sound sources and receiving systems varied from 10 to 300 km.     

Mechanism of photoluminescence excitation of Mn<Superscript>2+</Superscript> ions in ZnS crystals

The mechanisms of photoluminescence excitation of Mn²⁺ ions in ZnS crystals have been investigated on the basis of complex analysis of the temperature dependences of the photoluminescence and photoluminescence-excitation spectra of ZnS:Mn crystals. The activation energy of a manganese luminescence center was estimated at E_a = 0.17 ± 0.05 eV. It is shown that E_a represents an energy band with a width ΔE_a = 0.1 eV, within which a manganese luminescence center can experience radiationless recombination. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 788–793, November–December, 2005.     

Investigation of the Photoluminescence of Individual Emission Bands of Mn2+ Ions in ZnS Plastically Strained Single Crystals

The photoluminescence spectra of ZnS : Mn plastically deformed single crystals are investigated. It is established that the plastic strain causes the relative concentrations of individual manganese emission centers to change together with conditions of excitation of the centers whose nearest environment has been rearranged upon plastic strain.     

Anomalous thermal expansion of InSe layered semiconductors in the low-temperature region

The temperature dependence of the linear thermal expansion coefficient (TEC) of an InSe single crystal in the (001) plane is measured in the temperature range 7–50 K. A peak in the thermal expansion is detected near T = 10 K, after which the sample shrinks upon heating. The effect of an external magnetic field of up to 6 T, which is parallel to the (001) plane, on the TEC is investigated. The observed partial suppression of the peak and crystal compression by the field indicates the relation of these anomalies to possible electron ordering in InSe layers.     

Epitaxial growth of a graphene single crystal on the Ni(111) surface

The thermally controlled synthesis of graphene from propylene molecules on the Ni(111) surface in ultrahigh vacuum is studied by scanning tunneling microscopy and density functional theory. It is established that the adsorption of propylene on Ni(111) atomic terraces at room temperature results in the dehydration of propylene molecules with the formation of single-atomic carbon chains and in the complete dissociation of propylene at the edges of atomic steps with the subsequent diffusion of carbon atoms below the surface. The annealing of such a sample at 500°С leads to the formation of multilayer graphene islands both from surface atomic chains and by the segregation of carbon atoms collected in the upper nickel atomic layers. The process of formation of an epitaxial graphene monolayer until the complete filling of the nickel surface is controllably observed. Atomic defects seen on the graphene surface are interpreted as individual nickel atoms incorporated into graphene mono- or bivacancies.     

First results for the measurement of double-electron capture of 106Cd in the experiment TGV II

Present status of the experiment TGV II which is devoted to the measurement of double-beta decay of ¹⁰⁶Cd is given. The low background spectrometer TGV II is installed in the Modane Underground Laboratory and has been running from February 2005 with approx 10 grams of ¹⁰⁶Cd enriched at 75%. After an analysis of 3736 hours of experimental data the new improved half-life limit for 2νEC/EC decay of ¹⁰⁶Cd (0 _g.s. ⁺ → 0 _g.s. ⁺ ) is given as T ₁ ^2/2ν > 4.8 × 10¹⁹ years (90% CL). The search for 2νEC/EC decay of ¹⁰⁶Cd to the excited states of ¹⁰⁶Pd allows to determine the limits of the half-lives T ₁ ^2/2ν (0 _g.s. ⁺ → 2 ₁ ⁺ ) > 3.9 × 10¹⁹ years (90% CL) and T ₁ ^2/2ν (0 _g.s. ⁺ → 0 ₁ ⁺ ) > 5.8 × 10¹⁹ years (90% CL). Presented by I. Štekl at the Workshop on calculation of double-beta-decay matrix elements (MEDEX’05), Corfu, Greece, September 26–29, 2005.     

Temperature dependence of photoluminescence and electroluminescence of ZnS:Mn crystals

By means of comprehensive analysis of the temperature dependences of the photoluminescence for ZnS:Mn crystals, we have observed persistent changes in the intensity, shape, and position of the maximum in the emission spectrum associated with changes in the immediate environment of the manganese luminescence centers. We have also observed inflection points on the voltage vs. brightness characteristics of the samples, the position of which depends on the frequency of the exciting voltage and the temperature. The observed dependences are explained using concepts describing the mechanisms of pre-breakdown luminescence. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 631–636, September–October, 2006.     

Die Anwendung der Methode der zeitlich korrelierten assoziierten Teilchen (MEZKAT)

The TCAPM was developed to absolute and precise fission cross section measurement for neutron energies from 2 MeV up to 19 MeV. Experimental results of absolute fission cross section measurements on ²³³U, ²³⁵U, ²³⁸U, -²³⁷Np, ²³⁹Pu and ²¹²Pu are given. Furthermore the TCAPM is suitable for the application of inelastic scattering of neutrons by the analysis of element contents.     

Ensembles of aluminum islands on the surface of strained poly(ethylene terephthalate) films

This paper reports on a study of the size distribution of aluminum islands forming an aluminum-coated poly(ethylene terephthalate) film subjected to tension. The islands are shown to form four statistical ensembles, with the distribution in each of them being thermodynamically optimized and coinciding with the canonic distribution of thermodynamic probability.