Laser spectroscopy of radioactive molecules for future searches of new physics

This work presents theoretical, experimental, and technical progress on the spectroscopy of short-lived radioactive molecules that have been identified for their great promise as probes for fundamental, nuclear, chemical, and astrophysical research. The presented doctoral work includes the study of the nuclear charge radius in molecular spectra through the derivation of the molecular King-plot analysis. Moreover, new measurements from the broadband laser spectroscopy of radium monofluoride (RaF) and actinium monofluoride (AcF) are analyzed and presented, which have been proposed for their exceptional sensitivity to nuclear, hadronic, and leptonic moments that violate parity and time-reversal symmetries. The measurements were obtained with the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, CERN’s radioactive ion beam facility. In the case of AcF, this thesis stands as the first work that reports spectroscopic results on the molecule, which is of interest also for research in physical chemistry and nuclear medicine. Lastly, technical developments in the form of a voltage-scanning setup and a new laser-ablation ion source for the CRIS experiment are outlined, aimed at performing faster and more sensitive molecular spectroscopy of radioactive and non-radioactive molecules in the future. The results of this work are of high importance for the development of accurate and precise molecular theory, which in turn is crucial for the future endeavors of precision spectroscopy to test the limits of the Standard Model and to search for new physics using short-lived radioactive molecules.