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Aufsatz
Calculation of the electronic properties of neutral and ionized divalent-metal clusters
(1993)
The electronic properties of neutral and ionized divalent-metal clusters have been studied using a microscopic theory, which takes into account the interplay between van der Waals (vdW) and covalent bonding in the neutral clusters, and the competition between hole delocalization and polarization energy in the ionized clusters. By calculating the ground-state energies of neutral and ionized. Hg_n clusters, we determine the size dependence of the bond character and the ionization potential I_p(n). For neutral Hg_n ...
Aufsatz
On the transition from localized to delocalized electronic states in divalent-metal clusters
(1991)
The transition from van der Waals to covalent bonding, which is expected to occur in divalent-metal clusters with increasing cluster size, is discussed. We propose a model which takes into account, within the same electronic theory, the three main competing contributions, namely the kinetic energy of the electrons, the Coulomb interactions between electrons, and the s \gdw p intraatomic transitions responsible for van der Waals like bonding. The model is solved by taking into account electron correlations using a ...
Aufsatz
Femtosecond probing of sodium cluster ion Na_n ^+ fragmentation
(1992)
We report on the first femtosecond time-resolved experiments in cluster physics. The photofragmentation
dynamics of small sodium cluster ions Na_n ^+ have been studied with pump-probe techniques. Ultrashort
laser pulses of 60-fs duration are employed to photoionize the sodium clusters and to probe the
photofragments. We find that the ejection of neutral dimer Na_2 and, observed for the first time, neutral
trimer Na_3 photofragments occur on ultrashort time scales of 2.5 and 0.4 ps, respectively. This and the
absence ...
Aufsatz
Calculations of the polycentric linear molecule H^2+_3 with the finite element method
(1993)
A fully numerical two-dimensional solution of the Schrödinger equation is presented for the linear polyatomic molecule H^2+_3 using the finite element method (FEM). The Coulomb singularities at the nuclei are rectified by using both a condensed element distribution around the singularities and special elements. The accuracy of the results for the 1\sigma and 2\sigma orbitals is of the order of 10^-7 au.
Aufsatz
Elastic nuclear scattering at intermediate and relativistic energies
(1990)
The classical scattering cross section of two colliding nuclei at intermediate and relativistic energies is reevaluated. The influence of retardation and magnetic field effects is taken into account. Corrections due to electron screening as well as due to attractive nuclear forces are discussed. This paper represents an addendum to [l].
Aufsatz
Femtosecond spectroscopy of molecular autoionization and fragmentation
(1990)
Femtosecond laser pulses are applied to the study of the dynamics and the pathways of multiphoton-induced ionization, autoionization, and fragmentation of Na_2 in molecular-beam experiments. In particular,
we report on first results obtained studying electronic autoionization (leading to Na_2{^+} + {e ^-}) and
autoionization-induced fragmentation (leading to Na{^+} + Na + {e ^-}) of a bound doubly excited molecular state. The final continuum states are analyzed by photoelectron spectroscopy and by measuring the ...