Photodissociation studies of xanthene dyes, iron(III) azido complexes and hemithioindigo molecular switches in the gas phase

Electronic excitation triggered by the absorption of light enables numerous chemical, physical and biological processes and transformations. Accordingly, full control over the processes involving excited molecules requires an in-depth knowledge of electronic UV/vis spectra and potential energy surfaces. Unsurprisingly, most electronic spectra are acquired in the condensed phase in which molecules are dissolved and most transformations occur. However, our knowledge of excitation, transformations and processes at the level of isolated molecules is still limited, partly because such studies require unconventional experimental approaches and equipment. This Thesis describes experimental methods for recording electronic spectra of isolated molecules in the gas phase by ion spectroscopy, which combines mass spectrometry with optical spectroscopy. Using these methods, experimental factors which affect the electronic excitation and therefore the electronic spectra of ions were determined and evaluated for various fluorescent xanthene dyes, iron-containing complexes and molecular pho- toswitches. Furthermore, factors which govern photochemical processes, such as photo- oxidation, photoreduction and photoisomerization, were also analyzed in detail, with surprisingly different outcomes from previous studies..