Licentiate thesis: Multiphoton Ionisation of Atoms and Molecules Studied by Time-of-Flight Photoelectron Spectroscopy
by
Tomasz Kloda(SU Fysikum)
→
Europe/Stockholm
FD51
FD51
Description
Multiphoton ionisation (MPI) is a process in which an atom or a molecule irradiated by the
intense light absorbs several photons and subsequently splits into a positive ion and a free
electron. This process constitutes an important area for the exploration of the light-matter
interaction under, previously inaccessible, intense field conditions.
Experimental studies of the MPI require a well-controlled light source and a precise
instrumentation for the energy resolved electron detection. Such a setup, consisting of a solid
state ultrafast laser and a high efficiency time-of-flight electron spectrometer was recently
assembled at Stockholm University.
This thesis contains a detailed description and characterisation of the setup as well as the
experimental results obtained by the MPI of molecular oxygen and xenon. In the course of
photoionisation studies, O2 and Xe are frequently compared to each other due to their almost
equal ionisation potentials. However, our experimental results not only confirm that there are
substantial differences in mechanisms of molecular and atomic MPI, but also prove the
existence of several ionisation pathways in the oxygen case. Some of these pathways exhibit
surprising features which may require a further study.
