## Search

Now showing items 1-10 of 132

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Aufsatz
New calculations of P(b) curves for 1s_\sigma excitation in low-Z (Z\le10) ion-atom scattering

(1986)

Ab initio fully relativistic SCF molecular calculations of energy eigenvalues as well as coupling-matrix elements are used to calculate the 1s_\sigma excitation differential cross section for Ne-Ne and Ne-O in ion-atom collisions. A relativistic perturbation treatment which allows a direct comparison with analogous non-relativistic calculations is also performed.

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Aufsatz
Observation of two-electron-one-photon transitions in silicon

(1977)

We report on the observation of K\alpha\alpha X-rays of Si, produced in collisions of 15-28 MeV Si projectiles with various target atoms in the range Z =6 to 29. Energy shifts of X-rays were measured and are compared with theoretical predictions. Cross section ratios for emission of K\alpha\alpha and K\alpha radiation are given.

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Aufsatz
Relativistic ab initio calculations for ion-atom collisions

(Richard, Patrick (Hrsg.), 1993)

Within the independent particle model we solve the time-dependent single-particle equation using ab initio SCF-DIRAC-FOCK-SLATER wavefunctions as a basis. To reinstate the many-particle aspect of the collision system we use the inclusive probability formalism to answer experimental questions. As an example we show an application to the case of S{^15+} on Ar where experimental data on the K-K charge transfer are available for a wide range of impact energies from 4.7 to 90 MeV. Our molecular adiabatic calculations and ...

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Aufsatz
Ions of the superheavy elements in vacuum and in solution

(1976)

The extension of the Periodic Table into the range of unknown atomic numbers of above
one hundred requires relativistic calculations. The results of the latter are used to indicate probable values for X-ray transition lines which will be useful for identification of the atomic species formed
during collision between accelerated ions and the target. If the half-lives of the isotopes are long, then the chemistry of these new species becomes an important question which is reviewed for E110, E 111
and E112.
The ...

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Aufsatz
A clear atomic example for the surface sensitivity of penning ionization

(1990)

Using a crossed-beam apparatus with a double hemispherical electron spectrometer,
we have studied the spectrum of electrons released in thermal energy ionizing collisions of metastable
He^*(2^3S) atoms with ground state Yb(4f^14 6s^2 ^1S_0) atoms, thereby providing the first Penning electron spectrum of an atomic target with-4f-electrons. In contrast to the HeI (58.4nm) and NeI (73.6/74.4nm)
photoelectron spectra of Yb, which show mainly 4f- and 6s-electron emission in about a 5:1 ratio, the He^*(2^3S) Penning ...

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Aufsatz
Precision laser spectroscopy of the ground state hyperfine splitting of hydrogenlike ^209 Bi^82+

(1994)

The first direct observation of a hyperfine splitting in the optical regime is reported. The wavelength of the M1 transition between the F = 4 and F = 5 hyperfine levels of the ground state of hydrogenlike ^209 Bi^82+ was measured to be \lamda_0 = 243.87(4) nm by detection of laser induced fluorescence at the heavy-ion storage ring ESR at GSI. In addition, the lifetime of the laser excited F = 5 sublevel was determined to be \tau_0 = 0.351(16) ms. The method can be applied to a number of other nuclei and should allow ...

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Aufsatz
Relativity and screening effects in heavy-ion collisions

(1975)

Diatomic correlation diagrams are the main basis for the description of heavy-ion collisions. We have constructed the first realistic relativistic many-electron correlation diagrams based on nonrelativistic self-consistent-field, Hartree-Fock calculations of diatomic molecules plus relativistic corrections. We discuss the relativistic influences as well as the many-electron screening effects in the I-Au system with a combined charge of Z = 132 as an example.

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Aufsatz
On the correlation between electric polarizabilities and the ionization potential of atoms

(1985)

It is found that the electric dipole polarizabilities of neutral atoms correlate very strongly with their first ionization potential within the groups of elements with the same angular momenta of the outermost electrons. As the latter values are known very accurately, this allows a very good
(<30%) prediction of various atomic polarizabilities.

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Aufsatz
Self-consistent relativistic molecular calculations of superheavy molecules: (_110 X)F_6

(1978)

Using new relativistic molecular calculations within the Dirac-Slater scheme it is now
feasible to study theoretically molecules containing superheavy elements. This opens a
new era for the prediction of the physics and chemistry of superheavy elements. As an
example we present the results for (_110 X) F_6, where it is shown that relativistic effects are nearly of the same order of magnitude as the crystal-field splitting.