Physical Review A

Hyperfine structure in photoassociative spectra of Li26 and Li27

E. R. I. Abraham, W. I. McAlexander, Henk T. C. Stoof, Randall G. Hulet

Published May 1, 1996• 27 citations

Abstract

We present spectra of hyperfine resolved vibrational levels of the ${\mathit{A}}^{1}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{u}}^{+}$and 1${\mathrm{}}^{3}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ states of $^{6}\mathrm{Li}_{2}$ and $^{7}\mathrm{Li}_{2}$ obtained via photoassociation of colliding ultracold atoms in a magneto-optical trap. A simple first-order perturbation theory analysis accurately accounts for the frequency splittings and relative transition strengths of all observed hyperfine features. Assignment of the hyperfine structure allows accurate determination of a vibrational level center of gravity, which significantly decreases the experimental uncertainty of vibrational energies. Differences in the spectra of $^{6}\mathrm{Li}_{2}$ and $^{7}\mathrm{Li}_{2}$ are attributed to quantum statistics. The 1${\mathrm{}}^{3}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ series obeys Hund's case ${\mathit{b}}_{\mathrm{\ensuremath{\beta}}\mathit{S}}$ coupling and the hyperfine constant is extracted for both isotopes. \textcopyright{} 1996 The American Physical Society.

DOI: 10.1103/physreva.53.3092

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Photoassociative Spectroscopy of Collisions Between Ultracold Lithium Atoms

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Photoassociative spectroscopy of long-range states of ultracold 6Li2 and 7Li2

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Observation and analysis of the hyperfine structure of near-dissociation levels of the NaCs cΣ+3 state below the dissociation limit 3S1/2+6P3/2

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Physical Review A

Hyperfine structure in photoassociative spectra of Li26 and Li27

E. R. I. Abraham, W. I. McAlexander, Henk T. C. Stoof, Randall G. Hulet

Published May 1, 1996• 27 citations

Publisher

Abstract

We present spectra of hyperfine resolved vibrational levels of the

{\mathit{A}}^{1}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{u}}^{+}

and 1

{\mathrm{}}^{3}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}

states of

^{6}\mathrm{Li}_{2}

and

^{7}\mathrm{Li}_{2}

obtained via photoassociation of colliding ultracold atoms in a magneto-optical trap. A simple first-order perturbation theory analysis accurately accounts for the frequency splittings and relative transition strengths of all observed hyperfine features. Assignment of the hyperfine structure allows accurate determination of a vibrational level center of gravity, which significantly decreases the experimental uncertainty of vibrational energies. Differences in the spectra of

^{6}\mathrm{Li}_{2}

and

^{7}\mathrm{Li}_{2}

are attributed to quantum statistics. The 1

{\mathrm{}}^{3}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}

series obeys Hund's case

{\mathit{b}}_{\mathrm{\ensuremath{\beta}}\mathit{S}}

coupling and the hyperfine constant is extracted for both isotopes. \textcopyright{} 1996 The American Physical Society.

DOI: 10.1103/physreva.53.3092

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Photoassociative Spectroscopy of Collisions Between Ultracold Lithium Atoms

E. Abraham

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.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.

Jan 1, 19960 citations

Photoassociative spectroscopy of ultracold lithium(2)-7 and lithium(2)-6

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We have obtained high-lying vibrational spectra for the $\\rm 1\\sp3\\Sigma\\sbsp{g}{+}$ and $\\rm 1\\sp1\\Sigma\\sbsp{u}{+}$ excited states of both $\\rm \\sp7Li\\sb2$ and $\\rm \\sp6Li\\sb2$ via photoassociation of colliding ultracold lithium atoms confined in a magneto-optical trap. Photoassociative spectroscopy of ultracold atoms is a powerful tool for probing molecular states near the dissociation energy that are inaccessible by other methods. For an ultracold lithium vapor, the distribution of unbound ground state energies is so small that precise free-bound spectroscopy is possible. Molecular hyperfine structure is resolved. We calculate accurate dissociation energies for both the $\\rm 1\\sp3\\Sigma\\sbsp{g}{+}$ and $\\rm 1\\sp1\\Sigma\\sbsp{u}{+}$ excited states of Li $\\sb2$ . A model potential is constructed from a combination of experimental and theoretical information, and used to assign vibrational quantum numbers. We observe rotational structure and assign rotational quantum numbers.We have obtained high-lying vibrational spectra for the $\\rm 1\\sp3\\Sigma\\sbsp{g}{+}$ and $\\rm 1\\sp1\\Sigma\\sbsp{u}{+}$ excited states of both $\\rm \\sp7Li\\sb2$ and $\\rm \\sp6Li\\sb2$ via photoassociation of colliding ultracold lithium atoms confined in a magneto-optical trap. Photoassociative spectroscopy of ultracold atoms is a powerful tool for probing molecular states near the dissociation energy that are inaccessible by other methods. For an ultracold lithium vapor, the distribution of unbound ground state energies is so small that precise free-bound spectroscopy is possible. Molecular hyperfine structure is resolved. We calculate accurate dissociation energies for both the $\\rm 1\\sp3\\Sigma\\sbsp{g}{+}$ and $\\rm 1\\sp1\\Sigma\\sbsp{u}{+}$ excited states of Li$\\sb2$. A model potential is constructed from a combination of experimental and theoretical information, and used to assign vibrational quantum numbers. We observe rotational structure and assign rotational quantum numbers.

Jan 1, 19950 citations

Photoassociative spectroscopy of long-range states of ultracold 6Li2 and 7Li2

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We have obtained spectra of the high-lying vibrational levels of the A1Σu+ and 13Σg+states of both 6Li2 and 7Li2 via photoassociation of colliding ultracold atoms confined to a magneto-optical trap. Because of the low collision energies (∼1 mK), very high spectroscopic resolution is realized, and sensitivity is greatest for the usually difficult to access long-range states. Binding energies relative to the center of gravity of the resolved hyperfine structure are given for the A1Σu+ vibrational levels v =62–88 for 6Li2 and v=65–97 for 7Li2, and the 13Σg+ vibrational levels v=56–84 for 6Li2 and v=62–90 for 7Li2. These are extremely long-range levels with outer classical turning points ranging from 25 a0 to 220 a0, where a0 is the Bohr radius. The spectra arise mainly from s-wave collisions, and therefore exhibit little rotational structure.We have obtained spectra of the high-lying vibrational levels of the A1Σu+ and 13Σg+states of both 6Li2 and 7Li2 via photoassociation of colliding ultracold atoms confined to a magneto-optical trap. Because of the low collision energies (∼1 mK), very high spectroscopic resolution is realized, and sensitivity is greatest for the usually difficult to access long-range states. Binding energies relative to the center of gravity of the resolved hyperfine structure are given for the A1Σu+ vibrational levels v =62–88 for 6Li2 and v=65–97 for 7Li2, and the 13Σg+ vibrational levels v=56–84 for 6Li2 and v=62–90 for 7Li2. These are extremely long-range levels with outer classical turning points ranging from 25 a0 to 220 a0, where a0 is the Bohr radius. The spectra arise mainly from s-wave collisions, and therefore exhibit little rotational structure.

The Journal of Chemical PhysicsNov 8, 199591 citations

Molecular hyperfine structure in the photoassociation spectroscopy of laser cooled atoms

Carl J. Williams, Paul S. Julienne

The photoassociation of colliding ultracold trapped atoms permits the observation of high resolution molecular spectra of high lying vibrational levels with low total angular momentum and outer turning points greater than 50 Å. This paper describes how the hyperfine structure of alkali dimer molecules at large internuclear separation can be used to assign the electronic character of the observed photoassociation spectra and how hyperfine structure helps to explain the observed photoassociation spectrum of the attractive electronic states of the Na2 molecule that correlate with Na(3 2S)+Na(3 2P3/2) atoms.The photoassociation of colliding ultracold trapped atoms permits the observation of high resolution molecular spectra of high lying vibrational levels with low total angular momentum and outer turning points greater than 50 Å. This paper describes how the hyperfine structure of alkali dimer molecules at large internuclear separation can be used to assign the electronic character of the observed photoassociation spectra and how hyperfine structure helps to explain the observed photoassociation spectrum of the attractive electronic states of the Na2 molecule that correlate with Na(3 2S)+Na(3 2P3/2) atoms.

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Saturation in heteronuclear photoassociation of 6Li7Li

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Observation and analysis of the hyperfine structure of near-dissociation levels of the NaCs cΣ+3 state below the dissociation limit 3S1/2+6P3/2

Wenliang Liu, Jizhou Wu, Jie Ma +4 more

We report photoassociation (PA) of ultracold Na and Cs atoms in a dual-species magneto-optical trap. Trap loss spectroscopy of the ultracold polar NaCs molecules formed by PA, which carries information about relative PA transition strengths, has been experimentally obtained by using highly sensitive modulation spectroscopy technique. The fine and hyperfine effects at near-dissociation levels of NaCs molecular $c\phantom{\rule{0.16em}{0ex}}^{3}\mathrm{\ensuremath{\Sigma}}^{+}$ state are observed and modeled. The interaction Hamiltonian is described in terms of the Hund's case ( $a$ ) coupling scheme. The molecular hyperfine structure of near-dissociation levels is simulated within a simplified model of four interacting vibrational levels belonging to different initially unperturbed electronic states. The results of the simulation infer that the interaction parameters of the observed near-dissociation levels are close to the asymptotic parameters of the pair of atoms. The coupling of the electronic states is essential for forming the hyperfine structure.We report photoassociation (PA) of ultracold Na and Cs atoms in a dual-species magneto-optical trap. Trap loss spectroscopy of the ultracold polar NaCs molecules formed by PA, which carries information about relative PA transition strengths, has been experimentally obtained by using highly sensitive modulation spectroscopy technique. The fine and hyperfine effects at near-dissociation levels of NaCs molecular $c\phantom{\rule{0.16em}{0ex}}^{3}\mathrm{\ensuremath{\Sigma}}^{+}$ state are observed and modeled. The interaction Hamiltonian is described in terms of the Hund's case ($a$) coupling scheme. The molecular hyperfine structure of near-dissociation levels is simulated within a simplified model of four interacting vibrational levels belonging to different initially unperturbed electronic states. The results of the simulation infer that the interaction parameters of the observed near-dissociation levels are close to the asymptotic parameters of the pair of atoms. The coupling of the electronic states is essential for forming the hyperfine structure.

Physical Review ASep 30, 201622 citations

We present spectra of hyperfine resolved vibrational levels of the

{\mathit{A}}^{1}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{u}}^{+}

and 1

{\mathrm{}}^{3}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}

states of

^{6}\mathrm{Li}_{2}

and

^{7}\mathrm{Li}_{2}

^{6}\mathrm{Li}_{2}

and

^{7}\mathrm{Li}_{2}

are attributed to quantum statistics. The 1

{\mathrm{}}^{3}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}

series obeys Hund's case

{\mathit{b}}_{\mathrm{\ensuremath{\beta}}\mathit{S}}

coupling and the hyperfine constant is extracted for both isotopes. \textcopyright{} 1996 The American Physical Society.

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.

We have obtained high-lying vibrational spectra for the

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

and

\\rm 1\\sp1\\Sigma\\sbsp{u}{+}

excited states of both

\\rm \\sp7Li\\sb2

and

\\rm \\sp6Li\\sb2

via photoassociation of colliding ultracold lithium atoms confined in a magneto-optical trap. Photoassociative spectroscopy of ultracold atoms is a powerful tool for probing molecular states near the dissociation energy that are inaccessible by other methods. For an ultracold lithium vapor, the distribution of unbound ground state energies is so small that precise free-bound spectroscopy is possible. Molecular hyperfine structure is resolved. We calculate accurate dissociation energies for both the

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

and

\\rm 1\\sp1\\Sigma\\sbsp{u}{+}

excited states of Li

\\sb2

. A model potential is constructed from a combination of experimental and theoretical information, and used to assign vibrational quantum numbers. We observe rotational structure and assign rotational quantum numbers.

We report heteronuclear photoassociation spectroscopy in a mixture of magneto-optically trapped

{}^{6}\mathrm{Li}

and

{}^{7}\mathrm{Li}.

The laser-induced decrease in the

{}^{7}\mathrm{Li}

steady-state particle number, only appearing in the presence of

{}^{6}\mathrm{Li},

gives clear evidence of photoassociation to form

{}^{6}{\mathrm{Li}}^{7}\mathrm{Li}.

Hyperfine resolved spectra of the vibrational level

v=83

of the singlet state ${\mathrm{A}}^{1}{\ensuremath{\Sigma}}_{u}^{+}$ have been taken up to intensities of

1000{\mathrm{W}/\mathrm{c}\mathrm{m}}^{2}.

The absolute resonance frequencies and the rotational constant have been measured. Saturation of the photoassociation rate has been observed for two hyperfine transitions, which can be shown to be due to saturation of the rate coefficient near the unitarity limit. Saturation intensities on the order of

40{\mathrm{W}/\mathrm{c}\mathrm{m}}^{2}

can be determined.

a

) coupling scheme. The molecular hyperfine structure of near-dissociation levels is simulated within a simplified model of four interacting vibrational levels belonging to different initially unperturbed electronic states. The results of the simulation infer that the interaction parameters of the observed near-dissociation levels are close to the asymptotic parameters of the pair of atoms. The coupling of the electronic states is essential for forming the hyperfine structure.