Spectroscopy of the fine structure of lithium-like ions allows for some of the best precision tests of quantum electrodynamics (QED) calculations. In this work, the fine-structure doublet of lithium-like nitrogen, oxygen, neon, and argon ions were studied. For neon, the results are of comparable accuracy to the best laboratory data found in literature. The here reported values for argon are the first laboratory results and more accurate than those of previous solar observations, and in good agreement with recent ab initio full-scale QED calculations. A related subject is the search for a possible variation of the fine-structure constant α. Two highly forbidden transitions in neodymium-like iridium are among the best-suited ones for this search. In a systematic study, for the final determination of the upper and lower levels, 68 previously unknown emission lines were found and assigned to this species, almost doubling the number of known transitions. For these purposes, a normal-incidence spectrometer was developed. A high-performance electron beam ion trap (and source) was co-developed and commissioned for TRIUMF (Vancouver); while record-breaking specifications were achieved with it, the reported vacuum ultraviolet (VUV) work was carried out using a similar system at MPIK Heidelberg
