28 research outputs found
Fingerprints of slingshot non-sequential double ionization on two-electron probability distributions
We study double ionization of He driven by a near-single-cycle laser pulse at
low intensities at 400 nm. Using a three-dimensional semiclassical model, we
identify the pathways that prevail non-sequential double ionization (NSDI). We
focus mostly on the delayed pathway, where one electron ionizes with a
time-delay after recollision. We have recently shown that the mechanism that
prevails the delayed pathway depends on intensity. For low intensities
slingshot-NSDI is the mechanism that prevails. Here, we identify the
differences in two-electron probability distributions of the prevailing NSDI
pathways. This allows us to identify properties of the two-electron escape and
thus gain significant insight into slingshot-NSDI. Interestingly, we find that
an observable fingerprint of slingshot-NSDI is the two electrons escaping with
large and roughly equal energies.Comment: 9 pages, 5 figure
Triple photoionization of Lithium near threshold
Solving the full classical four-body Coulomb problem numerically using a
Wigner initial distribution we formulate a classical-quantum hybrid approach to
study triple ionization by single photon absorption from the Li ground state in
the threshold region.
We confirm the Wannier threshold law and we show
that the determined in the interval between 2-5 eV deviates from the
analytical threshold value of 2.16 which we find in the interval between
eV.Comment: 6 pages, 3 figure
Electron stripping and re-attachment at atomic centers using attosecond half-cycle pulses
We investigate the response of two three-body Coulomb systems when driven by
attosecond half-cycle pulses: The hydrogen molecular ion and the helium atom.
Using very short half-cycle pulses (HCPs) which effectively deliver ``kicks''
to the electrons, we first study how a carefully chosen sequence of HCPs can be
used to control to which of one of the two fixed atomic centers the electron
gets re-attached. Moving from one electron in two atomic centers to two
electrons in one atomic center we then study the double ionization from the
ground state of He by a sequence of attosecond time-scale HCPs, with each
electron receiving effectively a ``kick'' from each HCP. We investigate how the
net electric field of the sequence of HCPs affects the total and differential
ionization probabilities
Attosecond time-scale multi-electron collisions in the Coulomb four-body problem: traces in classical probability densities
In the triple ionization of the Li ground state by single photon absorption
the three electrons escape to the continuum mainly through two collision
sequences with individual collisions separated by time intervals on the
attosecond scale. We investigate the traces of these two collision sequences in
the classical probability densities. We show that each collision sequence has
characteristic phase space properties which distinguish it from the other.
Classical probability densities are the closest analog to quantum mechanical
densities allowing our results to be directly compared to quantum mechanical
results.Comment: 9 pages, 10 figure
Potential energy curves of molecular nitrogen up to
The potential energy curves for molecular ions up to are
calculated in an ab initio manner using the multi configurational
self-consistent field method. Specifically, we implement in an automatic way a
previously used double loop optimisation scheme within the multi
configurational self-consisted field method. We obtain the potential energy
curves up to ions with any combination of core, inner valence, and
outer valence holes. Finally, we provide the code used to generate these
potential energy curves.Comment: 20 pages, 16 figure
Multiple core hole formation by free-electron laser radiation in molecular nitrogen
We investigate the formation of multiple-core-hole states of molecular
nitrogen interacting with a free-electron laser pulse. We obtain bound and
continuum molecular orbitals in the single-center expansion scheme and use
these orbitals to calculate photo-ionization and Auger decay rates. Using these
rates, we compute the atomic ion yields generated in this interaction. We track
the population of all states throughout this interaction and compute the
proportion of the population which accesses different core-hole states. We also
investigate the pulse parameters that favor the formation of these core-hole
states for 525 eV and 1100 eV photons