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We theoretically investigate simultaneous double ionization of C60 Buckminsterfullerene clusters within the strong field approximation, taking into account two-body effects like Coulomb blocking. Our analysis suggests that for infrared single-cycle pulses, simultaneous double ionization becomes comparable in magnitude to sequential double ionization. Additionally, estimates show that Coulomb blocking weakens with increasing cluster size and field strength. Studienstiftung des Deutschen Volkeshttps://doi.org/10.13039/501100004350

The physical processes shaping laser plasma dynamics take place on length scales ranging from the microscopic (1 ångström) to the macroscopic realms (µm). Microscopic field fluctuations due to the motions of individual plasma charges evolve on an atomic scale. Collisional effects influencing thermalization and ionization processes depend on the plasma fields on an atomic level. Simultaneously, collective processes such as plasma oscillations take place on a mesoscopic length scale of many-nm. The macroscopic realm is ultimately determined by the laser which typically spans hundreds of nm to a few µm. Consequently, ab-initio modelling of laser plasma dynamics requires the resolution of length scales from 1Å to multiple µm. As such, in order to bridge the microscopic and macroscopic length scales of light-matter interaction, in is necessary to account for the individual motions of up to ~10^11 particles. This is a not an insignificant undertaking. Until recently, approaches to numerical modelling of light-matter interactions were limited to MD and PIC, each with their own limitations. MicPIC has been developed to fill the gap left by MD and PIC but so far has not been adapted for scalable parallel processing on large distributed memory machines. Thus, its full potential was not able to be fully realized until now. This thesis presents the massively parallel MicPIC method capable of bridging the micro- and macroscopic realms. A wide range of applications that have heretofore not been accessible to theory or, at best, had limited applicability are now open for thorough investigation. Among these are nonlinear nanophotonics, quantum nanophotonics, laser machining, ab-initio dynamics of strongly coupled plasmas, high-harmonic generation, electron and x-ray sources, and optical switching. Two of the first applications of parallel MicPIC to a selection of such problems are shown and discussed below, demonstrating the applicability of the method to a wide variety of newly accessible strong field laser-plasma physics phenomena.

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This thesis is an investigation of the charge conduction mechanism in deoxyribonucleic acid (DNA) molecules. In particular, we study the variable range hopping process and the effects which temperature and external electric field have upon it. The variable range hopping (VRH) conduction is assumed to be mediated by localized small polarons found on the base pairs, which hop in both energy and space coordinates. Phonons are created in the DNA by thermal and helical twisting motions assisting the hopping. A model of phonon assisted variable range small polaron hopping is developed while considering a constant density of electronic states near the Fermi level. The number of states available in a “hopping space” is calculated and the temperature and electric field dependent nearest neighbour hopping range is found. A T2/3power law is predicted for the conductance of DNA, whereas the behaviour of the electric field dependence is found to be primarily exponential. We apply these results to explain the experimental work and find that our model agrees well with the available data. To account for higher temperatures, a model of small polaron VRH conduction is developed using an exponential density of states. Through a process similar to that of the constant density of states, we derive a model which is found to agree well with the experimental results of a recent study. Additionally, an electric field dependence of the conductivity is developed to account for high electric fields.