Key step towards historic measurement of atomic parity violation in francium:
Francium Trapping Facility scientists made the first excitation of the highly forbidden 7s-8s transition on which future atomic-parity violation measurements will be based. As reported in Physical Review A (2018) the researchers scrutinized the accuracy of theoretical predictions of the overlap of the valence electron wavefunction with the nucleus (field shift) and electron-electron correlations (specific mass shift) in francium was carried out, another critical test towards understanding atomic theory in francium.