Manifestation of quasi-biennial oscillation in ozone vertical distribution

The quasi-biennial oscillations (QBO) in ozone and temperature vertical distributions are studied on the basis of ozonesonde data of 21 stations. Maximum QBO amplitudes in ozone are noted in the 16-20 kn layer over Resolute (75N), Aspendale (38S) and in the northern mid-latitude band, but in the 20-24 km layer in the northern subtropical band. In the upper layers the QBO effect is less evident. In the tropospheric layer it is difficult to note the QBO-related effect in all the groups of the data. In all the layers where the QBO effect is noted the positive deviations precede, but the negative deviations follow the time of maximum of the easterly equatorial wind at 50 mb level. No essential differences in phase or amplitude characteristics of the ozone QBO were noted for the Aspendale data compared with that for the Northern Hemisphere data. The QBO-effect is not noted in the temperature data in the mid-latitudes. Above Resolute and in subtropics the ozone and temperature effects are roughly in phase each with other, except in the 28-32 km layer over subtropics, where they are opposite each to other

Charge transfer transitions in the photoluminescence spectra of Zn1-xMexO (Me = Mn, Ni, Co) oxide compounds

Crystals of Zn1-xCoxO and Zn1-xNixO are studied by photoluminescence at temperatures of 8 and 90 K. By resolving the spectra into sums of gaussian distributions and using the known positions of donor and acceptor levels of 3d-impurities relative to the edges of the allowed bands, the observed peaks in the photoluminescence spectra are interpreted in terms of radiative recombination through donor and acceptor levels of nickel and cobalt ions. These results are compared with previously observed features of the photoluminescence spectra of Zn1-xMnxO crystals. © 2013 American Institute of Physics

The effect of the solar rotational irradiance variation on the middle and upper atmosphere calculated by a three-dimensional chemistry-climate model

This paper analyzes the effects of the solar rotational (27-day) irradiance variations on the chemical composition and temperature of the stratosphere, mesosphere and lower thermosphere as simulated by the three-dimensional chemistry-climate model HAMMONIA. Different methods are used to analyze the model results, including high resolution spectral and cross-spectral techniques. To force the simulations, an idealized irradiance variation with a constant period of 27 days (apparent solar rotation period) and with constant amplitude is used. While the calculated thermal and chemical responses are very distinct and permanent in the upper atmosphere, the responses in the stratosphere and mesosphere vary considerably in time despite the constant forcing. The responses produced by the model exhibit a non-linear behavior: in general, the response sensitivities (not amplitudes) decrease with increasing amplitude of the forcing. In the extratropics the responses are, in general, seasonally dependent with frequently stronger sensitivities in winter than in summer. Amplitude and phase lag of the ozone response in the tropical stratosphere and lower mesosphere are in satisfactory agreement with available observations. The agreement between the calculated and observed temperature response is generally worse than in the case of ozone

Mössbauer study of the surface of core-shell type nanoparticles

© 2016, Pleiades Publishing, Ltd.The properties of the surface layer of core-shell nanoparticles incorporated into the matrix of macromolecules of 3,4-bis(decyloxybenzoyl) poly(propylene imine) derivative of the second generation are studied by Mössbauer spectroscopy at low temperatures. The spin states, the details of the phonon spectrum and the Debye temperature of surface layer atoms discussed

Galkhaita

Los análisis de Gal-Khaya y Khaidarkan dieron, respectivamente, Hg 47,60, 49,02; Cu 3,49, 2,85; Zn 3,00, 0,60; Fe 0,31, nada ; Tl 0,46, 2,90; As 23,60, 19,49; Sb 0,59, 5,51; S 21,00, 19,31; Se 3 ppm, 150 ppm; total 100,05, 99,695 %.(...

Blue shift in optical absorption, magnetism and light-induced superparamagnetism in γ-Fe2O3 nanoparticles formed in dendrimer

© 2015, Springer Science+Business Media Dordrecht. Abstract: We are presenting the investigation of the optical, magnetic, and photoinduced superparamagnetic properties of single-domain γ-Fe2O3 nanoparticles (NPs) with diameters of about 2.5 nm formed in second-generation poly(propylene imine) dendrimer. The optical absorption studies indicated direct allowed transition with the band gap (4.5 eV), which is blue shift with respect to the value of the bulk material. Low-temperature blocking of the NPs magnetic moments at 18 K is determined by SQUID measurements. The influence of pulsed laser irradiation on the superparamagnetic properties of γ-Fe2O3 NPs was studied by EPR spectroscopy. It has been shown that irradiation of the sample held in vacuo and cooled in zero magnetic field to 6.9 K leads to the appearance of a new EPR signal, which decays immediately after the irradiation is stopped. The appearance and disappearance of this new signal can be repeated many times at 6.9 K when we turn on/turn off the laser. We suppose that the generation of conduction band electrons by irradiation into the band gap of the γ-Fe2O3 changes the superparamagnetic properties of NPs. Graphical Abstract: [Figure not available: see fulltext.]Features of the behavior of single-domain γ-Fe2O3 nanoparticles formed in dendrimer were found by UV-Vis and EPR spectroscopy: “blue” shift in optical absorption, a significant increase in the band gap width and variation of superparamagnetic properties under light irradiation

Optical properties and photoinduced superparamagnetism of γ-Fe<inf>2</inf>O<inf>3</inf> nanoparticles formed in dendrimer

© 2014 Elsevier Ltd. All rights reserved. We are presenting the joint investigation of the optical and photoinduced superparamagnetic properties of a single-domain γ-Fe2O3 nanoparticles (NPs) formed in poly(propylene imine) (PPI)-dendrimer. The optical absorption studies indicated direct allowed transition with the band gap (4.5 eV), which is blue-shift with respect to the value of the bulk material. The influence of pulsed laser irradiation on the superparamagnetic properties of γ-Fe2O3 NPs was studied by Electron paramagnetic resonance (EPR) spectroscopy. It has been shown that irradiation of the sample in vacuo and cooled in zero magnetic field to 6.9 K leads to the appearance of a new EPR signal, which decays immediately after the irradiation is stopped. We suppose that the generation of conduction band electrons by irradiation into the band gap of the γ-Fe2O3 changes the superparamagnetic properties of NPs

Cyclic Variation of Residual (CO2 + H2O) and Total Pressure in Conifer Stem and Woody Root Tree Rings

Tree-ring chronologies of stem discs and core samples have been widely used to reconstruct the climatic conditions of tree growth. However, insufficient attention has been given to the fact that root and stem wood accumulate biogenic gases, whose distribution in annual rings can also be related to the climate-dependent features of tree growth. The study of chronologies of gas samples extracted under vacuum from the wood of tree-ring discs of the Siberian stone pine (Pinus sibirica Du Tour), Scots pine (Pinus sylvestris L.), Siberian larch (Larix sibirica Ledeb.) and Siberian spruce (Picea obovata Ledeb.) suggests that annual distributions of CO2 and H2O in the rings and pressure variation in extracted samples follow a cyclic pattern. It was found that the sample pressure and the content of CO2 and H2O in the annual rings in stems and roots of the Siberian stone pine and Scots pine from Tomsk (Russia) area are characterized by varied time cycles, including periods of about 4 and 11 years, the latter corresponding to the period of the solar activity cycle. The four-year cycle in the above chronologies is explained by the presence of similar cycles in temperature and precipitation chronologies, where cyclic variations of CO2 in the rings can be interpreted as a response of the plant to the change in the climatic conditions. The established cyclic variation of the pressure and CO2 content in tree rings in stems and roots indicates that CO2 release into the atmosphere should also follow a cyclic pattern. Therefore, to estimate correctly the release of CO2 by tree stems and large roots, long-term measurements are require

Coexistence of spin crossover and magnetic ordering in a dendrimeric Fe(III) complex

© 2015 AIP Publishing LLC. The magnetic properties of a new dendrimeric spin crossover Fe(III) complex, [Fe(L)2]+PF6, where L = 3,5-di[3,4,5-tris(tetradecyloxy) benzoyloxy]benzoyl-4-salicylidene-N-ethyl-N-ethylene-diamine, are reported for the first time. EPR studies show that this compound undergoes a gradual spin transition in the temperature range 70-300K and has antiferromagnetic ordering below 10K. Mössbauer spectroscopy at 5K confirms the presence of magnetic ordering in the dendrimeric iron complex

Structural, magnetic and dynamic characterization of liquid crystalline iron(III) Schiff base complexes with asymmetric ligands

The iron(III) complexes that were formed by coordination of the Fe III ion with the asymmetric tridentate liquid crystalline Schiff base ligand (L), the water molecules and the different counterions [PF 6 - (1), NO3 - (2), and Cl- (3)] were studied by electron paramagnetic resonance (EPR) spectroscopy. EPR spectroscopy demonstrated that each of the complexes investigated consists of two types of iron centers: S = 1/2 low-spin (LS) and S = 5/2 high-spin (HS). LS iron complexes 2, 3 and LS complex 1 in the temperature range 4.2-250 K have a (dxz,dyz)4(dxy)1 ground state. Interesting features werefound for the monocationic FeIII complex 1, [Fe(L)X(H2O)2]+X-, with X = PF6 - as the counterion. The LS and HS iron centers of 1 are coupled together antiferromagnetically and form a dimer structure by means of the water molecules and the PF6 - counterion. The second-type of LS and HS centers that are visible by means of EPR spectroscopy were best observed in the liquid crystalline (387-405 K) phase. The monitoring and the simulation of the EPR spectra enabled us to trace the dynamics of changing the number of the second-type of LS centers with respect to the first-type of LS centers. The observed dynamic process is characterized by the enthalpy value ΔH = 27.9 kJ/mol, which was caused by reorientation of the PF6 - counterion. Calculation of the observed g values for the second-type of LS complex 1 indicated that, in this case, the (d xy)2(dxz,dyz)3 ground state is stabilized. The conversion between the electron (dxz,d yz)4(dxy)1/(dxy) 2(dxz,dyz)3 configurations was found to be temperature dependent and was detected in the same material for the first time in iron complexes. We synthesized a novel compound, namely a liquid crystalline iron(III) Schiff base complex with the asymmetric ligand [Fe(L)X(H2O)2]+X-, where X = PF 6 - is the counterion. This compound has a labilelow-spin electron configuration that switches between the (dxz,d yz)4(dxy)1/(dxy) 2(dxz,dyz)3 ground states and is temperature-dependent. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim