Optische Spektroskopie von Kationen in Neonmatrizen

Astronomy outside of our solar system is almost exclusively restricted to the recording of electromagnetic waves. A rich variety of spectroscopic information is always embedded in this continuous stream of light.
The aim of this thesis is to discover and interpret new spectroscopic data of ions and radicals. Electronic, vibrational and rotational states have been characterised for more than 200 small polyatomic ions. In most cases, these are ions of relatively stable molecules in their neutral state. However, ions of unstable molecules in their neutral form have very rarely been characterised spectroscopically in spite of their abundance in interstellar space, nebulae, comets as well as chemical reactions like plasma, combustion and radiation chemistry.
In this thesis, the first well-resolved spectrum of the diatomic ion C2+ (~B4.SIGMA.u- .rarw. ~X4.SIGMA.g- transition) has been successfully assigned and reported. (For the correct typographical representation of the formulae please refer to the pictorial information in this thesis: https://edoc.unibas.ch/82191/)
Furthermore, a new apparatus has been developed for the first time in order to facilitate the assignment of new spectral lines. To start with, a standard neon matrix isolation apparatus is used to record new absorption and emission spectra in the ultraviolet, visible and infrared range. This instrument has been extended with a quadrupole mass spectrometer serving as the new ion source. The novel combination of previously separate technologies has proved to be a cornucopia of new spectral information for years to come.
In an attempt to reduce impurities in the frozen neon matrices, the mass-selected ion beam has been transmitted via an octopole ion trap in order to facilitate the evacuation of potentially contaminating gases.
New absorption lines of isocyanogen cation CNCN+ have been discovered. This series of experiments demonstrated the limitations of mass selected ion deposition in rare gas matrices. Mass selection will not readily facilitate the interpretation of the results when isomerisation, and even worse fragmentation, of ions occur rapidly.