Stuttgart 2012 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 13: Photoionization
A 13.5: Vortrag
Dienstag, 13. März 2012, 11:30–11:45, V55.01
Precise determination of the ionization potential of astatine by in-source laser spectroscopy — •Sebastian Rothe1,2, Valentin Fedosseev1, Nobuaki Imai1, Bruce Marsh1, Marica Sjödin3, Maxim Seliverstov1, and Klaus Wendt2 — 1CERN, Geneva, Switzerland — 2Institut für Physik, Uni Mainz, Germany — 3GANIL, Caen, France
On-line in-source laser resonance ionization spectroscopy of the exclusively radioactive element astatine was performed at CERN/ISOLDE, representing the first ever laser spectroscopy on that heaviest halogen element. An efficient ionization scheme was developed and the first precise determination of the ionization potential of astatine atoms was carried out. Due to the absence of long lived isotopes of astatine, on-line production at the ISOLDE isotope separator facility at CERN was required. During a first measurement campaign, the ionization potential was located within a range of 100 cm−1 by photoionization threshold spectroscopy. This work was a prerequisite for the precision spectroscopy of high lying Rydberg states which was performed by scanning one of the RILIS lasers across the corresponding wavelength range. The observed Rydberg levels converge towards the ionization potential which was determined as 75151(1) cm−1. The efficient ionization scheme for astatine will also enable further precision in-source spectroscopy of isotope shifts and hyperfine structure as well as the study of beta delayed fission of the isotopes 194−199At.