Stuttgart 2012 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 14: Poster 2: Biomolecules, Electronic Spectroscopy, Experimental Techniques, Quantum Chemistry, Various Topics
MO 14.9: Poster
Mittwoch, 14. März 2012, 16:30–19:00, Poster.IV
Improved potential energy curve of the X1Σg+ state of Mg2 — •Horst Knöckel, Steffen Rühmann, and Eberhard Tiemann — QUEST und Inst.f. Quantenoptik, Leibniz Universität Hannover
Alkaline earth atoms are candidates for the development of optical clocks because of their narrow optical transitions promising much higher frequency stability and accuracy than for the present Cs-based microwave clocks. For ultimate accuracy the cold collision properties of the atoms must be known. Thus precise knowledge of the molecular potential energy curves (PEC) is important. For Ca2 and Sr2 ground and excited states have been characterized precisely while the information for Mg is less complete. For the investigation Mg2 vapor was produced in a heat pipe and absorption spectroscopy with a UV Fourier transform spectrometer yielded a dense spectrum, which was analyzed with a dedicated computer program to account for the severe overlap of lines due to the various isotopologues and the high temperature population distribution of molecular levels. These measurements were extended with additional recordings of laser induced fluorescence from UV lines of an Ar+ laser and from a frequency doubled TiSa laser, whose frequencies were selected to characterize levels of the ground state as close as possible to the dissociation limit. The accuracy of the line frequencies is better by about a factor of four compared to previous work. The transition frequencies were modeled by potential energy curves for both upper and lower states. For the ground state various PEC models and for the upper state the present status of evaluation will be presented.