8 research outputs found
Photoionization of the fullerene ion C60+
Photoionization cross section of the fullerene ion C60+ has been calculated
within a single-electron approximation and also by using a consistent many-body
theory accounting for many-electron correlations.Comment: 8 pages, 3 figure
Vacancy decay in endohedral atoms: the role of non-central position of the atom
We demonstrate that the Auger decay rate in an endohedral atom is very
sensitive to the atom's location in the fullerene cage. Two additional decay
channels appear in an endohedral system: (a) the channel due to the change in
the electric field at the atom caused by dynamic polarization of the fullerene
electron shell by the Coulomb field of the vacancy, (b) the channel within
which the released energy is transferred to the fullerene electron via the
Coulomb interaction. % The relative magnitudes of the correction terms are
dependent not only on the position of the doped atom but also on the transition
energy \om. Additional enhancement of the decay rate appears for transitions
whose energies are in the vicinity of the fullerene surface plasmons energies
of high multipolarity. % It is demonstrated that in many cases the additional
channels can dominate over the direct Auger decay resulting in pronounced
broadening of the atomic emission lines. % The case study, carried out for
Sc@C, shows that narrow autoionizing resonances in an
isolated Sc within the range \om = 30... 45 eV are dramatically
broadened if the ion is located strongly off-the-center. % Using the developed
model we carry out quantitative analysis of the photoionization spectrum for
the endohedral complex ScN@C and demonstrate that the additional
channels are partly responsible for the strong modification of the
photoionization spectrum profile detected experimentally by
M\"{u}ller et al. (J. Phys.: Conf. Ser. 88, 012038 (2008)).Comment: 32 pages, 11 figure
Confinement resonances in photoionization of endohedral atoms: a myth or reality?
We demonstrate that the structure of confinement resonances in the
photoionization cross section of an endohedral atom is very sensitive to the
mean displacement of the atom from the cage center. The resonances are
strongly suppressed if 2 exceeds the photoelectron half-wavelength. We
explain the results of recent experiments which contradict the earlier
theoretical predictions on the existence of confinement resonances in
particular endohedral systems.Comment: 4 pages, 5 figures, RevTe
Interplay of the volume and surface plasmons in the electron energy loss spectra of C
The results of a joint experimental and theoretical investigation of the C60
collective excitations in the process of inelastic scattering of electrons are
presented. The shape of the electron energy loss spectrum is observed to vary
when the scattering angle increases. This variation arising due to the electron
diffraction of the fullerene shell is described by a new theoretical model
which treats the fullerene as a spherical shell of a finite width and accounts
for the two modes of the surface plasmon and for the volume plasmon as well. It
is shown that at small angles, the inelastic scattering cross section is
determined mostly by the symmetric mode of the surface plasmon, while at larger
angles, the contributions of the antisymmetric surface plasmon and the volume
plasmon become prominent.Comment: 11 pages, 3 figure