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Abstract:
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.
