348 research outputs found
Atomic swelling upon compression
The hydrogen atom under the pressure of a spherical penetrable confinement
potential of a decreasing radius is explored, as a case study. A novel
counter-intuitive effect of atomic swelling rather than shrinking with
decreasing is unraveled, when reaches, and remains smaller
than, a certain critical value. Upon swelling, the size of the atom is shown to
increase by an order of magnitude, or more, compared to the size of the free
atom. Examples of changes of photoabsorption properties of confined hydrogen
atom upon its swelling are uncovered and demonstrated.Comment: 5 pages, 4 figure
Ground state properties of a confined simple atom by C fullerene
We numerically study the ground state properties of endohedrally confined
hydrogen (H) or helium (He) atom by a molecule of C. Our study is based
on Diffusion Monte Carlo method. We calculate the effects of centered and small
off-centered H- or He-atom on the ground state properties of the systems and
describe the variation of ground state energies due to the C parameters
and the confined atomic nuclei positions. Finally, we calculate the electron
distributions in plane in a wide range of C parameters.Comment: 23 pages, 9 figures. To appear in J.Phys. B: Atom. Mol. Op
Magneto-optical rotation of spectrally impure fields and its nonlinear dependence on optical density
We calculate magneto-optical rptation of spectrally impure fileds in an
optically thick cold atmic medium. We show that the spectral impurity leads to
non-linear dependence of the rotation angle on optical density. Using our
calculations, we provide a quanttative analysis of the recent experimental
results of G. Labeyrie et al. [Phys. Rev. A 64, 033402 (2001)] using cold
Rb atoms.Comment: 6 pages, 5 Figures, ReVTeX4, Submitted to PR
Term-dependent hybridization of the 5 f-wave functions of Ba and Ba++
It is shown that, unlike in neutral Ba, the 4d→5f transitions cannot be neglected in the interpretation of the 4d spectrum of Ba++. A term-dependent hybridization of the 5f wave functions occurs, the effects of which reverse between Ba and Ba++, and oscillator strength reappears in the 4d→nf (n>~5) transitions. A second kind of wave-function collapse is identified and its effects are described
Coherent Control of Magneto-optical Rotation in Inhomogeneously Broadened Medium
We extend our earlier investigations [Opt. Commun. {\bf 179}, 97 (2000)] on
the enhancement of magneto-optical rotation (MOR) to include inhomogeneous
broadening. We introduce a control field that counter-propagates with respect
to the probe field. We derive analytical results for the susceptibilities
corresponding to the two circular polarization components of the probe field.
From the analytical results we identify and numerically demonstrate the
region of parameters where significantly large magneto-optical rotation (MOR)
can be obtained. From the numerical results we isolate the significance of the
magnetic field and the control field in enhancement of MOR. The control field
opens up many new regions of the frequencies of the probe where large
magneto-optical rotation occurs. We also report that a large enhancement of MOR
can be obtained by operating the probe and control field in two-photon
resonance condition.Comment: REVTex format, 14 pages including 6 figures, to be published in
Optics Communication
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
Calculation of ground- and excited-state energies of confined helium atom
We calculate the energies of ground and three low lying excited states of
confined helium atom centered in an impenetrable spherical box. We perform the
calculation by employing variational method with two-parameter variational
forms for the correlated two-particle wave function. With just two variational
parameters we get quite accurate results for both ground and excited state
energies.Comment: 13 pages, No figur
On the possibility to consider fullerene shell C60 as a conducting sphere
Correctness of the model representing the fullerene shell C60 as a conducting
sphere has been analyzed. The static and dynamical polarizabilities of the
molecule C60 have been calculated on the basis of experimental data on the
photo-absorption cross- section of fullerene. It has been shown that the real
C60 in the static electric field behaves most likely as a set of separate
carbon atoms rather than as a conducting sphere and its static polarizability
exceeds by more than two times that of conducting sphere.Comment: 5 pages, 2 figure
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