Determination of the first ionization energy of polonium by resonance ionization spectroscopy - part I: Measurement of even-parity Rydberg states at TRIUMF-ISAC

Rydberg levels in the atomic spectrum of the element polonium (Po, Z = 84) were investigated using two-step laser resonance ionization spectroscopy in order to probe and determine the first ionization potential with high accuracy. As polonium has no stable isotopes, laser resonance ionization spectroscopy was carried out in-source at the Isotope Separator On-Line (ISOL) facility where the radioisotope 206Po was detected after mass separation. Evaluating the convergence of the observed Rydberg series results in a first ionization potential EIP(Po) = 8.418072(3)stat(15)systeV and more than 100 new even-parity Rydberg states belonging to 5 different series. The determined EIP is compared to available literature values and state of the art theoretical atomic many-body calculations. [Display omitted] •Resonance ionization spectroscopy of polonium with proton number Z = 84•Production of the isotope 206-Po at the isotope separator on-line facility TRIUMF•Identification of odd-parity Rydberg levels in the atomic structure of polonium•Determination of the first ionization potential of polonium