The interaction of intense few-cycle laser pulses with nanoscale targets
Author(s)
Skopalova, Eva
Type
Thesis
Abstract
In this thesis I describe investigations of the interaction of strong laser fields with nanoscale
targets, particularly with atomic clusters. I have explored laser-irradiated clusters in a new
regime of interaction where the pulse duration approaches the few-cycle regime and the cluster
ions essentially do not move during the laser pulse.
A key result of this thesis is the observation of a new anisotropy in the ion emission from
the explosion of xenon and argon clusters subjected to ultra-short (∼ 30 fs) near-infrared high
intensity (∼ 1015 Wcm−2) laser pulses. In this regime more energetic ions are emitted in the
direction perpendicular to the laser polarisation axis, which is the reverse of the well-known
anisotropy previously observed in experiments with longer (∼ 100 fs) pulses. I show that
the new anisotropy is a transient phenomenon present for a limited range of pulse durations,
that is specific to the cluster size and atom species. As the pulse duration is increased
the new anisotropy diminishes and a standard anisotropy appears. To explain the observed
anisotropy, I have developed an electrostatic model, showing that the intracluster electric field
can have a maximum in the direction perpendicular to the laser polarisation axis, leading to
anisotropic ion acceleration consistent with experimental observations. These measurements
and modeling give access to the initial dynamics, present early in the interaction of an intense
laser field with a nanoscale dielectric.
In addition to investigations of gas phase clusters I have also studied nanostructures on
surfaces. An experiment to study time-dependent plasmonic fields with attosecond streaking
is being designed and built. Here I present numerical simulations of nanoplasmonic streaking
and address the issues that have to be considered for the ongoing experiment. I show how
the plasmonic field can be retrieved from the simulated streaked spectra.
targets, particularly with atomic clusters. I have explored laser-irradiated clusters in a new
regime of interaction where the pulse duration approaches the few-cycle regime and the cluster
ions essentially do not move during the laser pulse.
A key result of this thesis is the observation of a new anisotropy in the ion emission from
the explosion of xenon and argon clusters subjected to ultra-short (∼ 30 fs) near-infrared high
intensity (∼ 1015 Wcm−2) laser pulses. In this regime more energetic ions are emitted in the
direction perpendicular to the laser polarisation axis, which is the reverse of the well-known
anisotropy previously observed in experiments with longer (∼ 100 fs) pulses. I show that
the new anisotropy is a transient phenomenon present for a limited range of pulse durations,
that is specific to the cluster size and atom species. As the pulse duration is increased
the new anisotropy diminishes and a standard anisotropy appears. To explain the observed
anisotropy, I have developed an electrostatic model, showing that the intracluster electric field
can have a maximum in the direction perpendicular to the laser polarisation axis, leading to
anisotropic ion acceleration consistent with experimental observations. These measurements
and modeling give access to the initial dynamics, present early in the interaction of an intense
laser field with a nanoscale dielectric.
In addition to investigations of gas phase clusters I have also studied nanostructures on
surfaces. An experiment to study time-dependent plasmonic fields with attosecond streaking
is being designed and built. Here I present numerical simulations of nanoplasmonic streaking
and address the issues that have to be considered for the ongoing experiment. I show how
the plasmonic field can be retrieved from the simulated streaked spectra.
Date Issued
2011-02
Date Awarded
2011-05
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Smith, Roland
Marangos, Jon
Creator
Skopalova, Eva
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)