Leibniz Universitt Hannover Spectroscopy of atom pairs and
Leibniz Universität Hannover Spectroscopy of atom pairs and collisions Eberhard Tiemann, Horst Knöckel (Gottfried Wilhelm Leibniz Universität Hannover) Asen Pashov (University Sofia) Olga Docenko, Maris Tamanis und Ruvin Ferber (University Riga)
Potential scheme of alkali dimers example Na. Rb (Korek et al 2000) Leibniz Universität Hannover Na fine structure Rb fine structure entrance channel high resolution Fourier spectroscopy entrance Spectroscopy of cold collisions
The spectroscopic workhorse Leibniz Universität Hannover Laser excitation high resolution Fourier spectroscopy entrance channel
Example Na. Rb Leibniz Universität Hannover
Overlap of X 1 S+ and a 3 S+ X a N = 19 Leibniz Universität Hannover shape resonance compare spacing exchange energy
Diagram of Evaluation Leibniz Universität Hannover common asymptote
Spectroscopic results of molecule AB Leibniz Universität Hannover Ground states Description of hyperfine interaction Asymptotic atomic values are sufficient! Fermi contact interaction Potentials for X 1 S+ and a 3 S+ and their long range behavior analytic form correlations between Ci exchange energy molecular potentials from short range to almost prediction of cold collisions? ! Excited states Hyperfine structure not or only poorly seen! Potentials represented by spline interpolation: shelf structure or double well possible Transition moments from ab initio calculations probably sufficiently good
Spectroscopy of cold collisions Leibniz Universität Hannover Molecular entrance channel transfer to atom pair continuum preparation of quantum state energy resolution by laser width Example Na 2 Samuelis et al, PRA 63, 012710 (2000) Atom pair entrance channel integration over energy distribution of cold ensemble tuning the embedded bound state structure Feshbach resonances
Combination of molecular and Feshbach resonance spectroscopy example 40 K 87 Rb Feshbach spectroscopy Leibniz Universität Hannover ensembles of Fermi and Bose atomic particles and Fermi molecular particles by LENS 2005, JILA 2006, Hamburg 2006, Hannover 2007 Analysis with asymptotic potential branches Derived quantities scattering lengths of “pure” singlet and triplet state da Hannover, Sofia, Riga 2006 ta of Molecular spectroscopy on 39 K 85 Rb and 39 K 87 Rb Born-Oppenheimer approximation yes Mass scaling of collision properties to other isotopes? s pe Describing the complete data set to iso Construction of “full” potentials probably reliable ? Continue with high precision experiments
Photoassociation Leibniz Universität Hannover Rb 2 Heinzen et al, Bloch et al singlet/triplet n 2 n 1 Na 2 Lett et al K 2 Stwalley et al KRb Stwalley et al pure triplet “pure” singlet n 2 - n 1 binding energy “Feshbach” molecules Transfer of “Feshbach” molecules to “deeply” bound states Rb 2 Hecker Denschlag et al
Summary and Conclusions on alkali dimers Leibniz Universität Hannover Full potentials at ground state asymptote “available” with sufficient accuracy in progress Li. Cs, Na. Rb, Na. Cs, KRb Li. K, KCs, Li. Rb Na 2 , K 2 (Li, Rb, Cs) Feshbach resonance structure very rich Binding energies from photoassociation desired Approximations: atomic hyperfine interaction neglected second order spin-orbit interaction Born-Oppenheimer approximation Electronic structure of excited states very complex Doorways to cold molecules with good predictions of transition moments from theory
KRb scattering lengths (units of a 0) Leibniz Universität Hannover Feshbach data deviations consistence LENS: Phys. Rev. A 73, 040702 (2006) erratum: Phys. Rev. A 74, 039903 (2006)
Coherent excitation scheme to the cold collision regime Leibniz Universität Hannover Example Na 2
Scattering spectroscopy 0 10 m. K kinetic energy Example Na+Na Comparison with simulation Leibniz Universität Hannover
Construction of the adiabatic ground state potentials inner part Ri (s) Ri (t) Ro(t, s) long range part Leibniz Universität Hannover energy (cm-1) 6000 continuous & @transition Ri 3000 fit to exp. data: V(R) = + a 1 x + a 2 x 2 + a 3 x 3 +. . . - D R-R x (R, b) = R + b. Re e 0 1 2 4 6 8 10 R(Å) 20 40 60
Spectrum for state a 3 S+ Leibniz Universität Hannover
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