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Abstract:
The goal of this work is to study and understand dynamics of atomic
systems interacting with strong fields. To this end, a method referred to as strong-field
spectroscopy is used, which measures the absorption spectrum of atoms interacting with
such fields. In the scope of this work, a technique which allows the simultaneous measurement
of absorption spectra of attosecond pulses and their reference signal is developed,
which significantly increases the sensitivity to absorption changes. Additionally, a reconstruction
method is introduced which retrieves the time-dependent evolution of the dipole
response of an atomic system directly from a single absorption spectrum. Strong-field
spectroscopy combines these techniques to examine the nonlinear strong-field dynamics
in atomic and molecular systems and is applied to study the strongly correlated doubly
excited states in helium. Furthermore, a measurement approach is introduced which uses
the interaction with a high-intensity laser pulse to impose a time gate on the evolution
of the coherent response of a system, which has previously been excited by an ultrashort
laser pulse. With this approach the buildup of resonance phenomena in a wide range of
physical systems can be studied. As a first application, the time-dependent buildup of a
Fano resonance as well as the buildup of a whole Rydberg series are investigated.
