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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
Femtosecond pump-probe study of the spreading and recurrence of a vibrational wave packet in Na_2
(1992)
The motion of a vibrational wave packet in the bound A(^1 \summe^+_u) electronic state of the sodium dimer is detected in a femtosecond pump/probe molecular beam experiment. For short times harmonic motion is seen in the total ion yield of Na^+_2 as a function of delay time between the two laser pulses. The spreading of the wave packet results in the loss of the periodic variation of the ion signal. For longer delay times (47 ps) the wave packet regains its initial form which is reflected in the revival structure of ...
Aufsatz
First results of experimental and theoretical investigations on sextet states of doubly-excited five-electron ions
(1992)
In continuation of our previous work on doubly-excited ions with three and four electrons we present the first results on optical transitions in the term system of doubly-excited ions with five electrons. Transitions between such sextet states were identified in beam-foil spectra of the ions nitrogen, oxygen and fluorine. Assignments were first established by comparison with Multi-Configuration Dirac-Fock calculations. Later assignments were aided by Multi-Configuration Hartree-Fock calculations (see the contribution ...
Aufsatz
Influence of the interaction potential on simulated sputtering and reflection data
(1992)
The TRIM.SP program which is based on the binary collision approximation was changed to handle not only repulsive interaction potentials, but also potentials with an attractive part. Sputtering yields, average depth and reflection coefficients calculated with four different potentials are compared. Three purely repulsive potentials (Meliere, Kr-C and ZBL) are used and an ab initio pair potential, which is especially calculated for silicon bombardment by silicon. The general trends in the calculated results are similar ...
Aufsatz
Interchannel interactions and relaxation in the 2p auger spectra of Mg-like ions
(1992)
Relativistic Auger rates for the 2p spectra of Mg-like ions have been calculated in the atomic range 13 < Z < 36. We used the multiconfiguration Dirac-Fock method but beyond a simple frozen-orbital approach we include also relaxation for the bound electrons and the interchannel interaction between the continuum states. Both effects may alter the individual transition rates remarkably. This is analysed for a few selected states within the isoelectronic sequence. Weak transitions within the 2p spectra can be changed ...
Aufsatz
Relativistic effects in physics and chemistry of element 105. [Part] II.
(American Institute of Physics, 1992)
Relativistic self-consistent charge Dirac-Slater discrete variational method calculations have been done for the series of molecules MBr_5, where M = Nb, Ta, Pa, and element 105, Ha. The electronic structure data show that the trends within the group 5 pentabromides resemble those for the corresponding pentaclorides with the latter being more ionic. Estimation of the volatility of group 5 bromides has been done on the basis of the molecular orbital calculations. According to the results of the theoretical interpretation ...
Aufsatz
Redox reactions of group 5 elements, including element 105, in aqueous solutions
(1992)
Standard redox potentials E^0(M^z+x/M^z+) in acidic solutions for group 5 elements including element 105 (Ha) and the actinide, Pa, have been estimated on the basis of the ionization potentials calculated via the multiconfiguration Dirac-Fock method. Stability of the pentavalent state was shown to increase along the group from V to Ha, while that of the tetra- and trivalent states decreases in this direction. Our estimates have shown no extra stability of the trivalent state of hahnium. Element 105 should form ...
Aufsatz
Relativistic effects in physics and chemistry of element 105. [Part] III.
(American Institute of Physics, 1992)
Electronic structures of MOCl_3 and MOBr_3 molecules, where M = V, Nb, Ta, Pa, and element 105, hahnium, have been calculated using the relativistic Dirac-Slater discrete variational method. The character of bonding has been analyzed using the Mulliken population analysis of the molecular orbitals. It was shown that hahnium oxytrihalides have similar properties to oxytrihalides of Nb and Ta and that hahnium has the highest tendency to form double bond with oxygen. Some peculiarities in the electronic structure of ...
Aufsatz
High laser field effects in multiphoton ionization of Na_2
(1992)
Femtosecond pump/probe multiphoton ionization experiments on Na_2 molecules are performed. The dependence of the total Na^+_2 ion signal on the delay time and the intensity of the femtosecond laser pulses is studied in detail. It is observed that molecular vibrational wavepacket motion in different electronic states dominates the time dependence of the ion signal. For higher laser intensities the relative contributions from the A ^1 \summe^+_u and the 2 ^1 \produkt__g states change dramatically, indicating the ...
Aufsatz
Application of inclusive probability theory to heavy ion-atom collisions
(1992)
Using the independent particle model as our basis we present a scheme to reduce the complexity and computational effort to calculate inclusive probabilities in many-electron collision system. As an example we present an application to K - K charge transfer in collisions of 2.6 MeV Ne{^9+} on Ne. We are able to give impact parameter-dependent probabilities for many-particle states which could lead to KLL-Auger electrons after collision and we compare with experimental values.