Hannover 2003 – wissenschaftliches Programm
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A: Atomphysik
A XI: HV XI
A XI.1: Hauptvortrag
Dienstag, 25. März 2003, 15:00–15:30, F342
Detailed laser spectroscopy studies of Rydberg series and narrow autoionizing resonances in gadolinium — •Klaus Blaum1, Bruce Bushaw2, Wilfried Nörtershäuser3, and Klaus Wendt4 — 1CERN, Division EP-IS, 1211 Geneva 23, Switzerland — 2PNNL, Richland, WA 99352, USA — 3GSI Darmstadt, Planckstraße 1, 64291 Darmstadt, Germany — 4Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
High-resolution laser spectroscopy has been performed to study the convergence of several even-parity J=5,6 Rydberg series in gadolinium. As a result, the ionization energy of 160Gd has been determined with nanovolt precision leading to a final value of 49601.5142(8) cm−1 or 6.14980335(10) eV. Furthermore the autoionization (AI) spectrum of gadolinium between the first and second limits has been investigated by triple-resonance excitation. Hundreds of narrow AI resonances have been observed and assigned total angular momentum J values. The resonances have been further divided into members of AI Rydberg series converging to the second limit or other ’interloping’ levels. A number of detailed studies have been performed on the interloping resonances: These include lifetime determination by lineshape analysis, isotope shifts, hyperfine structure, and photoionization saturation parameters. Linewidths are observed to generally decrease with increasing total angular momentum and the J = 7 resonances are extremely narrow with Lorentzian widths ranging from < 1 MHz up to 157 MHz. The strongest resonances are found to have cross-sections of 10−12 cm2 and photoionization can be saturated with powers available from cw diode lasers.