• Dynamics of excited atoms and molecules interacting with external fields 

      Simonsen, Sigrid Ina (Doctoral thesis; Peer reviewed, 2013-08-30)
      This thesis is a theoretical study of the behavior of electrons in atoms and molecules subjected to external electromagnetic fields. Three electronic systems have been central in this work, the atomic and quasimolecular ...
    • Femtosecond-pulse-train ionization of Rydberg wave packets 

      Simonsen, Sigrid Ina; Sørngård, Stian Astad; Førre, Morten; Hansen, Jan Petter (Peer reviewed; Journal article, 2012-10-09)
      We calculate, based on first-order perturbation theory, the total and differential ionization probabilities from a dynamic periodic Rydberg wave packet of a given n-shell exposed to a train of femtosecond laser pulses. The ...
    • High-order harmonic generation from graphene: Strong attosecond pulses with arbitrary polarization 

      Sørngård, Stian Astad; Simonsen, Sigrid Ina; Hansen, Jan Petter (Peer reviewed; Journal article, 2013-05-03)
      We explore high-order harmonic generation (HHG) from a graphene sheet exposed to intense femtosecond laser pulses based on the Lewenstein model. It is demonstrated that the HHG cutoff frequency increases with graphene size ...
    • Interatom intrashell blockade 

      Sælen, L.; Simonsen, Sigrid Ina; Hansen, Jan Petter (Peer reviewed; Journal article, 2011-01-07)
      We demonstrate a feature of the Rydberg blockade mechanism which occurs between two initially excited circular Rydberg atoms. When both atoms are exposed to weak time-dependent electric fields, it is shown that the intrashell ...
    • Long-range interactions and dynamics of excited atoms 

      Simonsen, Sigrid Ina (Master thesis, 2010-06-10)
      A study of the dynamics of excited hydrogenic atoms, with emphasis on analytical and numerical calculations of the time-independent and the time-dependent Schrõdinger equation. A short description of Rydberg atoms and their ...