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arXiv:1703.07752 · Physical Review A

Level structure of deeply bound levels of the c3Σg+ state of Rb287

Björn Drews, Markus Deiß, Joschka Wolf, E. Tiemann, Johannes Hecker Denschlag

Published Jun 23, 2017• 5 citations
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Abstract

We spectroscopically investigate the hyperfine, rotational, and Zeeman structure of the vibrational levels ${v}^{\ensuremath{'}}=0,7,13$ within the electronically excited $c{\phantom{\rule{0.222222em}{0ex}}}^{3}{\mathrm{\ensuremath{\Sigma}}}_{g}{}^{+}$ state of $^{87}\mathrm{Rb}_{2}$ for magnetic fields of up to $1000\phantom{\rule{0.28em}{0ex}}\text{G}$. As spectroscopic methods we use short-range photoassociation of ultracold Rb atoms as well as photoexcitation of ultracold molecules which have been previously prepared in several well-defined quantum states of the $a{\phantom{\rule{0.222222em}{0ex}}}^{3}\mathrm{\ensuremath{\Sigma}}{}_{u}^{+}$ potential. As a by-product, we present optical two-photon transfer of weakly bound Feshbach molecules into $a{\phantom{\rule{0.222222em}{0ex}}}^{3}\mathrm{\ensuremath{\Sigma}}{}_{u}^{+}$, $v=0$ levels featuring different nuclear spin quantum numbers. A simple model reproduces well the molecular level structures of the $c{\phantom{\rule{0.222222em}{0ex}}}^{3}{\mathrm{\ensuremath{\Sigma}}}_{g}{}^{+}$ vibrational states and provides a consistent assignment of the measured resonance lines. Furthermore, the model can be used to predict the relative transition strengths of the lines. From fits to the data we extract for each vibrational level the rotational constant, the effective spin-spin interaction constant, as well as the Fermi contact parameter and the anisotropic hyperfine constant. In an alternative approach, we perform coupled-channel calculations where we fit the relevant potential energy curves, spin-orbit interactions, and hyperfine functions. The calculations reproduce the measured hyperfine level term frequencies with an average uncertainty of $\ifmmode\pm\else\textpm\fi{}9\phantom{\rule{0.28em}{0ex}}\mathrm{MHz}$, similar as for the simple model. From these fits we obtain a section of the potential energy curve for the $c{\phantom{\rule{0.222222em}{0ex}}}^{3}{\mathrm{\ensuremath{\Sigma}}}_{g}{}^{+}$ state which can be used for predicting the level structure for the vibrational manifold ${v}^{\ensuremath{'}}=0$ to 13 of this electronic state.

DOI
10.1103/physreva.95.062507

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We report on photoassociation spectroscopy probing the ${c}^{3}{\mathrm{\ensuremath{\Sigma}}}_{1}^{+}$ potential of the bialkali NaCs molecule, identifying 11 vibrational lines between ${v}^{\ensuremath{'}}=0$ and ${v}^{\ensuremath{'}}=25$ of the excited ${c}^{3}{\mathrm{\ensuremath{\Sigma}}}_{1}^{+}$ potential and fitting their rotational and hyperfine structure. The observed lines are assigned by fitting to an effective Hamiltonian model of the excited-state structure with rotational and hyperfine constants as free parameters. We discuss unexpected broadening of select vibrational lines and its possible link to strong spin-orbit coupling of the ${c}^{3}{\mathrm{\ensuremath{\Sigma}}}_{1}^{+}$ potential with the nearby ${b}^{3}{\mathrm{\ensuremath{\Pi}}}_{1}$ and ${B}^{1}{\mathrm{\ensuremath{\Pi}}}_{1}$ manifolds. Finally, we report use of the ${v}^{\ensuremath{'}}=22$ line as an intermediate state for two-photon transfer of weakly bound Feshbach molecules to the rovibrational ground state of the ${X}^{1}{\mathrm{\ensuremath{\Sigma}}}^{+}$ manifold.
We present the results of an experimental and theoretical study of the electronically excited $(1){}^{3}{\ensuremath{\Sigma}}_{\mathrm{g}}^{+}$ state of 87Rb^{87}\mathrm{Rb}87Rb2{}_{2}2​ molecules. The vibrational energies are measured for deeply bound states from the bottom up to ${v}^{\ensuremath{'}}=15$ using laser spectroscopy of ultracold Rb2{}_{2}2​ Feshbach molecules. The spectrum of each vibrational state is dominated by a 47-GHz splitting into ${0}_{\mathrm{g}}^{\ensuremath{-}}$ and 1g{1}_{\mathrm{g}}1g​ components caused mainly by a strong second-order spin-orbit interaction. Our spectroscopy fully resolves the rotational, hyperfine, and Zeeman structure of the spectrum. We are able to describe this structure to the first order using a simplified effective Hamiltonian.
Mixing of 0+{0}^{+}0+ and 0−{0}^{-}0− observed in the hyperfine and Zeeman structure of ultracold Rb2{\mathrm{Rb}}_{2}Rb2​ molecules
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Analyzing the photoassociation spectra of ultracold 85^{85}85Rb133^{133}133Cs molecule in (3)3Σ+(3)^3Σ^+(3)3Σ+ state
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