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Title: The interaction of intense few-cycle laser pulses with nanoscale targets
Author: Skopalova, Eva
ISNI:       0000 0004 2703 7057
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2011
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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.
Supervisor: Smith, Roland ; Marangos, Jon Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral