Laboratory and stellar spectroscopy of the complex ions Fe+, Mo+, Th+ and U+

The new generation of high resolution astronomical instruments such as the Hubble Space Telescope (HST) or the Very Large Telescope (VLT) has renewed the demand for accurate atomic parameters like wavelengths, oscillator strengths and line profiles accompanied by reliable uncertainty estimates. Fourier transform spectroscopy has proven to be a powerful tool when measuring these parameters. In this thesis new oscillator strengths in Fe II, Mo II, Th II and U II measured with Fourier transform spectroscopy are presented together with a method of how to treat the uncertainties of f-values measured with the emission technique. An extended term analysis of Mo II is also presented, including more than 100 new energy levels. Calculated f-values for all classified Mo II transitions are included. Some astrophysical applications of the new atomic data are demonstrated