554 research outputs found
5s correlation confinement resonances in Xe-endo-fullerenes
Spectacular trends in the modification of the Xe 5s photoionization via
interchannel coupling with confinement resonances emerging in the Xe 4d giant
resonance upon photoionization of the Xe@C60, Xe@C240 and Xe@C60@C240
endo-fullerenes are theoretically unraveled and interpreted.Comment: 1 page, 1 figure. 2011 International Conference on Photonic,
Electronic, and Atomic Collisions (Belfast, UK, 2011). Paper number We15
Confinement induced orbital breathing, fusion, fission and re-ordering in semifilled shell atoms
Alternate contraction and drastic expansion, i.e., `breathing' of electronic
subshells, the effects of fusion of two subshells into one subshell and its
subsequent fission (splitting) into the original subshells, as well as multiple
alteration of the order of subshells in confined semifilled shell atoms with a
progressively narrowing confinement are theoretically discovered. The
confinement is represented by a repulsive penetrable spherical potential of an
inner radius . The effects are exemplified by calculated data for
confined semifilled shell atoms from the second, third and fourth rows of
Mendeleev's table - Li, N, P and Cr atoms with semifilled ,
, and subshells, respectively - for
the completeness of the study. The underlying physics behind the discovered
effects is explained.Comment: 15 pages, 7 figures; to be submitted to J. Phys. B: At. Mol. Opt.
Phy
Confinement and electron correlation effects in photoionization of atoms in endohedral anions: Ne@C60^{z-}
Trends in resonances, termed confinement resonances, in photoionization of
atoms A in endohedral fullerene anions A@C60^{z-} are theoretically studied and
exemplified by the photoionization of Ne in Ne@C{60}^{z-}. Remarkably, above a
particular nl ionization threshold of Ne in neutral Ne@C60 (I_{nl}^{z=0}),
confinement resonances in corresponding partial photoionization cross sections
sigma_{nl} of Ne in any charged Ne@C60^{z-} remain almost intact by a charge z
on the carbon cage, as a general phenomenon. At lower photon energies, omega <
I_{nl}^{z=0}, the corresponding photoionization cross sections develop
additional, strong, z-dependent resonances, termed Coulomb confinement
resonances, as a general occurrence. Furthermore, near the innermost 1s
ionization threshold, the 2p photoionization cross section sigma_{2p} of the
outermost 2p subshell of thus confined Ne is found to inherit the confinement
resonance structure of the 1s photoionization spectrum, via interchannel
coupling. As a result, new confinement resonances emerge in the 2p
photoionization cross section of the confined Ne atom at photoelectron energies
which exceed the 2p threshold by about a thousand eV, i.e., far above where
conventional wisdom said they would exist. Thus, the general possibility for
confinement resonances to resurrect in photoionization spectra of encapsulated
atoms far above thresholds is revealed, as an interesting novel general
phenomenon.Comment: 6 pages, 4 figures, Latex2e, jpconf.cls styl
Revivification of confinement resonances in the photoionization of @C endohedral atoms far above thresholds
It is discovered theoretically that significant confinement resonances in an
photoionization of a \textit{multielectron} atom encaged in carbon
fullerenes, A@C, may re-appear and be strong at photon energies far
exceeding the ionization threshold, as a general phenomenon. The reasons
for this phenomenon are unraveled. The Ne photoionization of the
endohedral anion Ne@C in the photon energy region of about a
thousand eV above the threshold is chosen as case study.Comment: 3 pages, 1 figure, Revtex
Xe 4d photoionization in Xe@C60, Xe@C240, and Xe@C60@C240
Re-evaluated parameters for the square-well potential model for
photoionization of endo-fullerenes are proposed and employed to reveal the
spectacular modifications in the Xe 4d photoionization giant resonance along
the path from Xe@C60 to Xe@C240 to multi-walled Xe@[email protected]: 1 page, 1 figure. 2011 International Conference on Photonic,
Electronic, and Atomic Collisions (Belfast, UK, 2011), abstract Tue13
Angle-differential elastic electron scattering off C: A simple semi-empirical theory versus experiment
We prove in the present paper that a simple modeling of a complicated highly
polarizable C target by a rectangular (in a radial coordinate) square
well potential in combination with the static polarization potential provides a
viable approximation for a low-energy elastic electron scattering off this
target. The proof is based on the results of the comparison of the calculated
angle-differential elastic electron scattering cross section off C
versus corresponding experimental data.Comment: 4 pages, 3 figure
Electron elastic scattering off a spin-polarized Cr atom
Electron elastic scattering off a spin-polarized Cr(...,
) atom is theoretically studied in the region of electron energies up to
eV using both a one-electron "spin-polarized" Hartree-Fock and
multielectron "spin-polarized" random phase approximation with exchange. It is
found that scattering phase shifts of oppositely spin-polarized incoming
electrons and corresponding cross sections of the scattering reactions
significantly differ from each other, in general, even without accounting for
spin-orbit interaction. This is shown to be associated with the presence of two
semifilled and subshells in the Cr's configuration which
induce considerably different exchange in the interaction of oppositely
spin-polarized incoming electrons with the atom-target. The importance of
electron correlation in elastic scattering process is revealed.
Moreover, correlation is shown to induce strong differences between scattering
of oppositely spin-polarized electrons off Cr. A physically transparent
interpretation for the latter is provided.Comment: 6 pages, 7 figures, submitted to Phys. Rev.
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