14,167 research outputs found
Bulk and thin films of FeTe: A Moessbauer study
Studies of bulk and thin films of FeTe using Moessbauer spectroscopy showed that FeTe has one noncubic Fe (+2) site which is 3d2 4s 4p3 hybridized. The presence of dangling bands was indicated in spectra of FeTe thin films. The films showed a tendency of texture formation. The substrate was observed to influence the film structure and nature of bonds in films
Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII
Energy levels, Land\'{e} -factors and radiative lifetimes are reported for
the lowest 182 levels of the 3d, 3d4s and 3d4p configurations of
Fe~V, Co~VI and Ni~VII. Additionally, radiative rates (-values) have been
calculated for the E1, E2 and M1 transitions among these levels. The
calculations have been performed in a quasi-relativistic approach (QR) with a
very large {\em configuration interaction} (CI) wavefunction expansion, which
has been found to be necessary for these ions. Our calculated energies for all
ions are in excellent agreement with the available measurements, for most
levels. Discrepancies among various calculations for the radiative rates of E1
transitions in Fe~V are up to a factor of two for stronger transitions (), and larger (over an order of magnitude) for weaker ones. The reasons for
these discrepancies have been discussed and mainly are due to the differing
amount of CI and methodologies adopted. However, there are no appreciable
discrepancies in similar data for M1 and E2 transitions, or the -factors for
the levels of Fe~V, the only ion for which comparisons are feasible.Comment: This paper of 78 pages including 9 Tables will appear in ADNDT (2016
Moessbauer study in thin films of FeSi2 and FeSe systems
Thin films of FeSi2 and FeSe were studied using Moessbauer spectroscopy information regarding dangling bond configuration and nature of crystal structure in thin films was derived. A significant influence of crystalline aluminum substrate on film structure was observed
Cumulative effect of Weibel-type instabilities in counterstreaming plasmas with non-Maxwellian anisotropies
Counterstreaming plasma structures are widely present in laboratory
experiments and astrophysical systems, and they are investigated either to
prevent unstable modes arising in beam-plasma experiments or to prove the
existence of large scale magnetic fields in astrophysical objects.
Filamentation instability arises in a counterstreaming plasma and is
responsible for the magnetization of the plasma. Filamentationally unstable
mode is described by assuming that each of the counterstreaming plasmas has an
isotropic Lorentzian (kappa) distribution. In this case, the filamentation
instability growth rate can reach a maximum value markedly larger than that for
a a plasma with a Maxwellian distribution function. This behaviour is opposite
to what was observed for the Weibel instability growth rate in a bi-kappa
plasma, which is always smaller than that obtained for a bi-Maxwellian plasma.
The approach is further generalized for a counterstreaming plasma with a
bi-kappa temperature anisotropy. In this case, the filamentation instability
growth rate is enhanced by the Weibel effect when the plasma is hotter in the
streaming direction, and the growth rate becomes even larger. These effects
improve significantly the efficiency of the magnetic field generation, and
provide further support for the potential role of the Weibel-type instabilities
in the fast magnetization scenarios
Electron Impact Excitation Cross Sections for Hydrogen-Like Ions
We present cross sections for electron-impact-induced transitions n --> n' in
hydrogen-like ions C 5+, Ne 9+, Al 12+, and Ar 17+. The cross sections are
computed by Coulomb-Born with exchange and normalization (CBE) method for all
transitions with n < n' < 7 and by convergent close-coupling (CCC) method for
transitions with n 2s and 1s
--> 2p are presented as well. The CCC and CBE cross sections agree to better
than 10% with each other and with earlier close-coupling results (available for
transition 1 --> 2 only). Analytical expression for n --> n' cross sections and
semiempirical formulae are discussed.Comment: RevTeX, 5 pages, 13 PostScript figures, submitted to Phys. Rev.
On fixed linear systems with a generalized performance criteria
Fixed linear systems with generalized performance criteri
Energy levels and radiative rates for transitions in Cr-like Co IV and Ni V
We report calculations of energy levels and radiative rates (-values) for
transitions in Cr-like Co IV and Ni V. The quasi-relativistic Hartree-Fock
(QRHF) code is adopted for calculating the data although GRASP (general-purpose
relativistic atomic structure package) and flexible atomic code (FAC) have also
been employed for comparison purposes. No radiative rates are available in the
literature to compare with our results, but our calculated energies are in
close agreement with those compiled by NIST for a majority of the levels.
However, there are discrepancies for a few levels of up to 3\%. The -values
are listed for all significantly contributing E1, E2 and M1 transitions, and
the corresponding lifetimes reported, although unfortunately no previous
theoretical or experimental results exist to compare with our data.Comment: The paper will appear in ADNDT (2016) and in October 2015 on the we
Protein adsorption on heterogeneous surfaces
The adsorption of the protein bovine serum albumin from an aqueous solution onto substrata made from pure silica, pure zirconia, and a mixture of the two has revealed that the adsorption behavior of the protein onto the mixture very significantly diverges from the corresponding mean of the behaviors with the pure substrata. A tentative explanation in terms of matching substratum heterogeneity with protein surface heterogeneity is offered
Interferometry of direct photons in Pb+Pb collisions at 158 AGeV
We present final results from the WA98 experiment which provide first
measurements of Bose-Einstein correlations of direct photons in
ultrarelativistic heavy ion collisions. Invariant interferometric radii were
extracted in the range MeV/c and compared to interferometric
radii of charged pions. The yield of direct photons for MeV/c was
extracted from the correlation strength parameter and compared to the yield of
direct photons measured in WA98 at higher with the statistical
subtraction method, and to predictions of a fireball model.Comment: 4 pages, 3 figures, proceedings for Quark Matter 200
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