18,800 research outputs found
Non-dipole angular anisotropy parameters of semi-filled shell atoms
We present the results of calculations of outer shell non-dipole angular
anisotropy parameters for semi-filled shell atoms in the Hartree-Fock (HF)
one-electron approximation and with account of inter-electron correlations in
the frame of the Spin Polarized Random Phase Approximation with Exchange (SP
RPAE). We demonstrate for the first time that this characteristic of
photoionization process is essentially sensitive to the fact whether the
photoelectron has the same or opposite spin orientation to that of the
semi-filled shell.Comment: 15 pages, 8 figure
Possible magnetic-field-induced voltage and thermopower in diluted magnetic semiconductors
In diluted magnetic semiconductors, the carrier concentration and the
magnetization of local moments are strongly coupled, since the magnetic
interaction is mediated by the carriers. It is predicted that this coupling
leads to an electric polarization due to an applied magnetic-field gradient and
to the appearance of a magnetic-field-dependent voltage. An expression for this
voltage is derived within Landau theory and its magnitude is estimated for
(Ga,Mn)As. Furthermore, a large contribution to the thermopower based on the
same mechanism is predicted. The role of fluctuations is also discussed. These
predictions hold both if the magnetization is uniform and if it shows
stripe-like modulations, which are possible at lower temperatures.Comment: 6 pages revtex, 5 figure
Photoionization of Xe 3d electrons in molecule Xe@C60: interplay of intra-doublet and confinement resonances
We demonstrate rather interesting manifestations of co-existence of resonance
features in characteristics of the photoionization of 3d-electrons in Xe@C60.
It is shown that the reflection of photoelectrons produced by the 3d Xe
photoionization affects greatly partial photoionization cross-sections of and
levels and respective angular anisotropy parameters, both dipole and non-dipole
adding to all of them additional maximums and minimums. The calculations are
performed treating the 3/2 and 5/2 electrons as electrons of different kinds
with their spins "up" and "down". The effect of C60 shell is accounted for in
the frame of the "orange" skin potential model.Comment: 13 pages, 12 figure
On Quantum Corrections to Chern-Simons Spinor Electrodynamics
We make a detailed investigation on the quantum corrections to Chern-Simons
spinor electrodynamics. Starting from Chern-Simons spinor quantum
electrodynamics with the Maxwell term and by calculating the vacuum polarization tensor,
electron self-energy and on-shell vertex, we explicitly show that the Ward
identity is satisfied and hence verify that the physical quantities are
independent of the procedure of taking at one-loop and
tree levels. In particular, we find the three-dimensional analogue of the
Schwinger anomalous magnetic moment term of the electron produced from the
quantum corrections.Comment: 16 pages, RevTex, no figures, A few typewritten errors have been
correcte
Spontaneous decay of excited atomic states near a carbon nanotube
Spontaneous decay process of an excited atom placed inside or outside (near
the surface) a carbon nanotube is analyzed. Calculations have been performed
for various achiral nanotubes. The effect of the nanotube surface has been
demonstrated to dramatically increase the atomic spontaneous decay rate -- by 6
to 7 orders of magnitude compared with that of the same atom in vacuum. Such an
increase is associated with the nonradiative decay via surface excitations in
the nanotube.Comment: 8 pages, 3 figure
Perturbations and absorption cross-section of infinite-radius black rings
We study scalar field perturbations on the background of non-supersymmetric
black rings and of supersymmetric black rings. In the infinite-radius limit of
these geometries, we are able to separate the wave equation, and to study wave
phenomena in its vicinities. In this limit, we show that (i) both geometries
are stable against scalar field perturbations, (ii) the absorption
cross-section for scalar fields is equal to the area of the event horizon in
the supersymmetric case, and proportional to it in the non-supersymmetric
situation.Comment: ReVTeX4. 15 pages, 3 figures. References added. Published versio
On the photoionization of the outer electrons in noble gas endohedral atoms
We demonstrate the prominent modification of the outer shell photoionization
cross-section in noble gas (NG) endohedral atoms NG@F under the action of the
fullerene F electron shell. This shell leads to two important effects, namely
to strong enhancement of the cross-section due to fullerenes shell polarization
under the action of the incoming electromagnetic wave and to prominent
oscillation of this cross-section due to the reflection of the photoelectron
from NG by the F shell.
All but He noble gas atoms are considered. The polarization of the fullerene
shell is expressed via the total photoabsorption cross-section of F. The
reflection of the photoelectron is taken into account in the frame of the
so-called bubble potential that is a spherical zero --thickness potential.
It is assumed in the derivations that NG is centrally located in the
fullerene. It is assumed also, in accord with the existing experimental data,
that the fullerenes radius R is much bigger than the atomic radius and the
thickness of the fullerenes shell . These assumptions permit, as it was
demonstrated recently, to present the NG@F photoionization cross-section as a
product of the NG cross-section and two well defined calculated factors.Comment: 19 pages, 9 figure
Suppression of Visibility in a Two-Electron Mach-Zehnder Interferometer
We investigate the suppression of the visibility of Aharonov-Bohm
oscillations in a two-electron Mach-Zehnder interferometer that leaves the
single-electron current unchanged. In the case when the sources emit either
spin-polarized or entangled electrons, partial distinguishability of electrons
(coming from two different sources) suppresses the visibility. Two-particle
entanglement may produce behavior similar to "dephasing" of two-particle
interferometry.Comment: 5 pages, 1 figur
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