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arXiv:1011.1319 · Physical Review A

Predicting and verifying transition strengths from weakly bound molecules

K. Aikawa, Daisuke Akamatsu, Masahiko Hayashi, Jun Kobayashi, Masahito Ueda, S. Inouye

Published Apr 11, 2011• 7 citations
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Abstract

We investigated transition strengths from ultracold weakly bound $^{41}\mathrm{K}$$^{87}\mathrm{Rb}$ molecules produced via the photoassociation of laser-cooled atoms. An accurate potential energy curve of the excited state $(3){}^{1}{\ensuremath{\Sigma}}^{+}$ was constructed by carrying out direct potential fit analysis of rotational spectra obtained via depletion spectroscopy. Vibrational energies and rotational constants extracted from the depletion spectra of ${v}^{'}=41$--50 levels were combined with the results of the previous spectroscopic study and they were used for modifying an ab initio potential. An accuracy of 0.14% in vibrational level spacing and 0.3% in rotational constants was sufficient to predict the large observed variation in transition strengths among the vibrational levels. Our results show that transition strengths from weakly bound molecules are a good measure of the accuracy of an excited state potential.

DOI
10.1103/physreva.83.042706

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We investigated transition strengths from ultracold weakly bound ^{41}\mathrm{K}$$^{87}\mathrm{Rb} molecules produced via the photoassociation of laser-cooled atoms. An accurate potential energy curve of the excited state (3)1\ensuremathΣ+(3){}^{1}{\ensuremath{\Sigma}}^{+}(3)1\ensuremathΣ+ was constructed by carrying out direct potential fit analysis of rotational spectra obtained via depletion spectroscopy. Vibrational energies and rotational constants extracted from the depletion spectra of v′=41{v}^{'}=41v′=41--50 levels were combined with the results of the previous spectroscopic study and they were used for modifying an ab initio potential. An accuracy of 0.14% in vibrational level spacing and 0.3% in rotational constants was sufficient to predict the large observed variation in transition strengths among the vibrational levels. Our results show that transition strengths from weakly bound molecules are a good measure of the accuracy of an excited state potential.
We report on the use of depletion spectroscopy to detect ultracold ground-state KRb molecules with rotational resolution. The population of a specific ground-state vibrational level ${v}^{\ensuremath{''}}$, produced by photoassociation of ultracold atoms, is monitored by one-color two-photon pulsed-laser ionization. When a cw laser is resonant with a rovibrational transition to an excited state, the ground-state population, and hence the ion signal, is depleted. This narrow-band spectroscopic technique allows the individual rotational levels in both ground and excited states to be resolved, and thus the population of a single ground-state rovibrational level to be monitored. These resolved transitions are a necessary first step in transferring population from high vibrational levels of the ground state, such as produced by photoassociation, to the absolute molecular ground state $X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}^{+}$ (${v}^{\ensuremath{''}}=0$, ${J}^{\ensuremath{''}}=0$). This technique can also be used to determine binding energies of high-${v}^{\ensuremath{''}}$ molecules. Combining our binding energy measurement with the results of previous spectroscopy yields an improved dissociation energy of the XXX state: ${D}_{e}=4217.822\ifmmode\pm\else\textpm\fi{}0.003\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$. We also report on the two-color pulsed-laser ionization used to locate the depletion transitions.
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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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