Mainz 2017 – scientific programme
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A: Fachverband Atomphysik
A 28: Ultracold Plasmas, Rydberg Systems and Molecules (with Q)
A 28.8: Talk
Thursday, March 9, 2017, 13:00–13:15, P 104
Precision two-color spectroscopy of 40Ca for the determination of the s-wave scattering length — •Veit Dahlke1, Evgenij Pachomow1, Eberhard Tiemann2, Fritz Riehle1, and Uwe Sterr1 — 1Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany — 2Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
By two-color photoassociation of 40Ca four weakly bound vibrational levels in the Ca2 X 1Σg+ ground state potential were measured,
using highly spin-forbidden transitions to intermediate states of the coupled system 3Πu and 3Σu+ near the 3P1+1S0 asymptote. We have interrogated cold ensembles of about 105 calcium atoms trapped in a crossed optical dipole trap at temperatures of approximately 1 µ K. The unperturbed binding energies have been measured with kHz accuracy benefiting from few Hertz linewidth offset-locked tunable lasers and detailed lineshape analysis.
From the observed binding energies, including the least bound state, the long range dispersion coefficients C6, C8,C10 and a precise value for the s-wave scattering length were derived. The precise description of the asymptotic potential was also used to determine scattering lengths for all stable isotopes of calcium.