Optical double resonance photoassociation spectrum of ground state Rb_2

R. S. Freeland, Chin‐Chun Tsai, Daniel J. Heinzen, J. M. M. J. Vogels, S. J. J. M. F. Kokkelmans, BOUDEWIJN J. VERHAAR

Published Apr 1, 1997• 0 citations

Abstract

We report the first observation of the highest lying bound levels of the ground electronic state of ^85Rb2 by means of optical double resonance (free-bound-bound) photoassociation spectroscopy of colliding, laser-cooled ^85Rb atoms. Twelve levels with binding energies from 0.13 to 20 Ghz are observed. We carry out an inverse perturbation analysis of these levels that takes full account of the hyperfine-induced singlet-triplet mixing with a coupled channels approach. This analysis yields previously undetermined atomic interaction parameters that are crucial for the understanding of Rb ultracold collisions and Bose-Einstein condensates. Complete consistency is obtained with all previously measured cold collision properties of Rb. We gratefully acknowledge the support at Texas of the R. A. Welch Foundation, the NSF, and the Microgravity Science and Applications Division of NASA.

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Optical double resonance photoassociation spectrum of ground state Rb_2

R. S. Freeland, Chin‐Chun Tsai, Daniel J. Heinzen, J. M. M. J. Vogels, S. J. J. M. F. Kokkelmans, BOUDEWIJN J. VERHAAR

Published Apr 1, 1997• 0 citations

OpenAlex

Abstract

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We determine the energies of twelve vibrational levels lying within 20 GHz of the lowest dissociation limit of ${}^{85}{\mathrm{Rb}}_{2}$ with two-color photoassociation spectroscopy of ultracold ${}^{85}\mathrm{Rb}$ atoms. The levels lie in an energy range for which singlet and triplet states are mixed by the hyperfine interaction. We carry out a coupled channels bound state analysis of the level energies, and derive accurate values for ${}^{85}{\mathrm{Rb}}_{2}$ interaction parameters. The information obtained is sufficient to allow for quantitative calculations of arbitrary Rb ultracold collision properties.We determine the energies of twelve vibrational levels lying within 20 GHz of the lowest dissociation limit of ${}^{85}{\mathrm{Rb}}_{2}$ with two-color photoassociation spectroscopy of ultracold ${}^{85}\mathrm{Rb}$ atoms. The levels lie in an energy range for which singlet and triplet states are mixed by the hyperfine interaction. We carry out a coupled channels bound state analysis of the level energies, and derive accurate values for ${}^{85}{\mathrm{Rb}}_{2}$ interaction parameters. The information obtained is sufficient to allow for quantitative calculations of arbitrary Rb ultracold collision properties.

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PHOTOASSOCIATION SPECTROSCOPY OF ${^{85}}Rb_{2}$ NEAR ITS DISSOCIATION LIMITPHOTOASSOCIATION SPECTROSCOPY OF ${^{85}}Rb_{2}$ NEAR ITS DISSOCIATION LIMIT

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Jan 1, 20100 citations

We determine the energies of twelve vibrational levels lying within 20 GHz of the lowest dissociation limit of

{}^{85}{\mathrm{Rb}}_{2}

with two-color photoassociation spectroscopy of ultracold

{}^{85}\mathrm{Rb}

atoms. The levels lie in an energy range for which singlet and triplet states are mixed by the hyperfine interaction. We carry out a coupled channels bound state analysis of the level energies, and derive accurate values for

{}^{85}{\mathrm{Rb}}_{2}

interaction parameters. The information obtained is sufficient to allow for quantitative calculations of arbitrary Rb ultracold collision properties.

PHOTOASSOCIATION SPECTROSCOPY OF

{^{85}}Rb_{2}

NEAR ITS DISSOCIATION LIMIT

We present results which probe the structure of

{^{85}}Rb_{2}

very near its lowest dissociation limit. To obtain these results, we used two different variations of photoassociation spectroscopy of laser-cooled and trapped

{^{85}}Rb

atoms. First, we have determined the positions of twelve of the highest vibrational levels of

{^{85}}Rb_{2}

, all bound by less than

0.7 cm^{-1}

, with two-color (free-bound-bound) photoassociation spectroscopy. The levels lie in an energy range for which singlet and triplet states are strongly mixed by the hyperfine interaction. We found that we could accurately describe these states with a novel coupled-channels inverse perturbation analysis. In a second experiment, we have carried out Zeeman-resolved photoassociation spectroscopy. This technique allowed us to probe the energy range in the lowest part of the electronic ground state continuum, which lies between the dissociation limits corresponding to different hyperfine states of the separated atoms. With this method, we have observed a Feshbach scattering resonance in the continuum for the first time, which we find can be tuned to zero energy with a magnetic field.

{}^{85}\mathrm{Rb}

gas. This analysis yields information on the interactions between ultracold

{}^{85}\mathrm{Rb}

atoms that is important to the understanding of ultracold Rb collisions and Bose-Einstein condensation.

The spectra of the high-lying vibrational levels of the

A\\sp1\\Sigma\\sbsp{u}{+}

and

1\\sp3\\Sigma\\sbsp{g}{+}

singly excited states of both

\\sp6\\rm Li\\sb2

and

\\sp7\\rm Li\\sb2

are obtained via photoassociation of colliding ultracold atoms confined in a magneto-optical trap. The least bound state of the

a\\sp3\\Sigma\\sbsp{u}{+}

ground state potential, obtained by two-photon photoassociative spectroscopy, is also presented for both

\\sp7\\rm Li\\sb2

and

\\sp6\\rm Li\\sb2

. The vibrational levels have resolved hyperfine structure, whose relative energy splittings and transition strengths are accurately modeled. The photoassociative spectra are used to precisely determine both the singlet and triplet s-wave scattering lengths for both isotopes, which are important parameters in systems designed to observe quantum degenerate effects and Bose-Einstein condensation.