Atomic Structure Revealed by EUV Photoabsorption of 6th Row Ions

Looking at the light emitted and absorbed by atoms has allowed us to characterize their behaviour for the last 150 years. How light is absorbed by atoms tells us how the atoms behave and how the particles inside them are arranged. The electrons that orbit the nucleus of an atom are responsible for the chemistry of the atom. When electrons are removed from atoms to create ions, the remaining electrons change their behaviour. The majority of ions remain unstudied by photoabsorption, the process by which light is passed through the atoms and selectively absorbed by the electrons. This project pushes the boundaries of photoabsorption research, studying 6th row atoms ionized up to 5 times in the 48 - 127 eV photon energy range and resolving the large resonance features that are attributed to their complex open-shell electronic structures. Almost no other photoabsorption studies have been undertaken on these ions in this region. Nd:YAG lasers were used to generate plasmas containing the ions of interest and plasmas emitting the continuum radiation used to probe them using the dual laser plasma (DLP) technique. Chapter 1 provides a general introduction to the physics of spectroscopy and it’s development over the last few centuries, which is followed by description of the relevant theory applied in this thesis in chapter 2. The experimental methodology in chapter 3 outlines how the experimental platinum data in chapter 4, and iridium data in chapter 5 were ascertained. The process of synthesizing Pt and Ir spectra is illustrated in the appendices, in addition to the details of the apparatus and spectra recorded across the 6th row.