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

E. Abraham

Published Jan 1, 1995• 0 citations

Abstract

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.

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Photoassociative Spectroscopy of Collisions Between Ultracold Lithium Atoms

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Precise determination of the 2P radiative atomic lifetime of lithium using photoassociative spectroscopy

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Jan 1, 19950 citations

Precise atomic radiative lifetime via photoassociative spectroscopy of ultracold lithium

W. I. McAlexander, E. R. I. Abraham, Nicholas W. M. Ritchie +3 more

Physical Review AFeb 1, 1995123 citations

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

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Hyperfine structure in photoassociative spectra of Li26 and Li27

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Physical Review AMay 1, 199627 citations

Molecular hyperfine structure in the photoassociation spectroscopy of laser cooled atoms

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The Journal of Chemical PhysicsAug 1, 199454 citations

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

E. Abraham

Published Jan 1, 1995• 0 citations

OpenAlex

Abstract

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.

Related papers

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

Precise determination of the 2P radiative atomic lifetime of lithium using photoassociative spectroscopy

W. I. McAlexander

Spectroscopy of the high-lying vibrational levels of the $1\\sp3\\Sigma\\sbsp{g}{+}$ and $1\\sp1\\Sigma\\sbsp{u}{+}$ states of both $\\rm\\sp6Li\\sb2$ and $\\rm\\sp7Li\\sb2$ has been accomplished via photoassociation of ultracold atomic lithium confined in a magneto-optical trap. Both these molecular states correlate to $2S\\sb{1/2}$ plus $2P\\sb{1/2}$ free atomic states. The long range part of these molecular potentials depends on the 2P atomic radiative lifetime. Accurate models were constructed for both the $1\\sp3\\Sigma\\sbsp{g}{+}$ and $1\\sp1\\Sigma\\sbsp{u}{+}$ potentials. By fitting these models to the experimentally measured vibrational levels observed in $\\rm\\sp6Li\\sb2$ and $\\rm\\sp7Li\\sb2$ , we have been able to extract a value for the 2P lifetime of lithium. Fitting to the absolute values of the data gives a value of 26.99 $\\pm$ 0.16 ns whereas fitting to differences in the spectral features gives a value of 27.04 $\\pm$ 0.18 ns. While both values agree with previous work, improvements made in the potential models would enable this analysis to resolve the current discrepancy between experiment and theory.Spectroscopy of the high-lying vibrational levels of the $1\\sp3\\Sigma\\sbsp{g}{+}$ and $1\\sp1\\Sigma\\sbsp{u}{+}$ states of both $\\rm\\sp6Li\\sb2$ and $\\rm\\sp7Li\\sb2$ has been accomplished via photoassociation of ultracold atomic lithium confined in a magneto-optical trap. Both these molecular states correlate to $2S\\sb{1/2}$ plus $2P\\sb{1/2}$ free atomic states. The long range part of these molecular potentials depends on the 2P atomic radiative lifetime. Accurate models were constructed for both the $1\\sp3\\Sigma\\sbsp{g}{+}$ and $1\\sp1\\Sigma\\sbsp{u}{+}$ potentials. By fitting these models to the experimentally measured vibrational levels observed in $\\rm\\sp6Li\\sb2$ and $\\rm\\sp7Li\\sb2$, we have been able to extract a value for the 2P lifetime of lithium. Fitting to the absolute values of the data gives a value of 26.99 $\\pm$ 0.16 ns whereas fitting to differences in the spectral features gives a value of 27.04 $\\pm$ 0.18 ns. While both values agree with previous work, improvements made in the potential models would enable this analysis to resolve the current discrepancy between experiment and theory.

Jan 1, 19950 citations

Precise atomic radiative lifetime via photoassociative spectroscopy of ultracold lithium

W. I. McAlexander, E. R. I. Abraham, Nicholas W. M. Ritchie +3 more

We have obtained spectra of the high-lying vibrational levels of the ${1}^{3}$ ${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ state of $^{6}\mathrm{Li}_{2}$ via photoassociation of ultracold $^{6}\mathrm{Li}$ atoms confined in a magneto-optical trap. The ${1}^{3}$ ${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ state of the diatomic molecule correlates to a 2 ${\mathit{S}}_{1/2}$ state atom plus a 2 ${\mathit{P}}_{1/2}$ state atom. The long-range part of the molecular interaction potential for this state depends on the 2P atomic radiative lifetime. By calculating the energy eigenvalues of a model potential for the ${1}^{3}$ ${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ state and fitting them to the experimentally measured vibrational levels, we have extracted a value for the 2P lifetime of 26.99\ifmmode\pm\else\textpm\fi{}0.16 ns. The precision is currently limited by the accuracy of a region of the model potential provided by ab initio calculations.We have obtained spectra of the high-lying vibrational levels of the ${1}^{3}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ state of $^{6}\mathrm{Li}_{2}$ via photoassociation of ultracold $^{6}\mathrm{Li}$ atoms confined in a magneto-optical trap. The ${1}^{3}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ state of the diatomic molecule correlates to a 2${\mathit{S}}_{1/2}$ state atom plus a 2${\mathit{P}}_{1/2}$ state atom. The long-range part of the molecular interaction potential for this state depends on the 2P atomic radiative lifetime. By calculating the energy eigenvalues of a model potential for the ${1}^{3}$${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ state and fitting them to the experimentally measured vibrational levels, we have extracted a value for the 2P lifetime of 26.99\ifmmode\pm\else\textpm\fi{}0.16 ns. The precision is currently limited by the accuracy of a region of the model potential provided by ab initio calculations.

Physical Review AFeb 1, 1995123 citations

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

E. R. I. Abraham, Nicholas W. M. Ritchie, W. I. McAlexander +1 more

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

Hyperfine structure in photoassociative spectra of Li26 and Li27

E. R. I. Abraham, W. I. McAlexander, Henk T. C. Stoof +1 more

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.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.

Physical Review AMay 1, 199627 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.

The Journal of Chemical PhysicsAug 1, 199454 citations

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

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

and

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

excited states of Li

\\sb2

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.

Spectroscopy of the high-lying vibrational levels of the

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

and

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

states of both

\\rm\\sp6Li\\sb2

and

\\rm\\sp7Li\\sb2

has been accomplished via photoassociation of ultracold atomic lithium confined in a magneto-optical trap. Both these molecular states correlate to

2S\\sb{1/2}

plus

2P\\sb{1/2}

free atomic states. The long range part of these molecular potentials depends on the 2P atomic radiative lifetime. Accurate models were constructed for both the

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

and

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

potentials. By fitting these models to the experimentally measured vibrational levels observed in

\\rm\\sp6Li\\sb2

and

\\rm\\sp7Li\\sb2

, we have been able to extract a value for the 2P lifetime of lithium. Fitting to the absolute values of the data gives a value of 26.99

\\pm

0.16 ns whereas fitting to differences in the spectral features gives a value of 27.04

\\pm

0.18 ns. While both values agree with previous work, improvements made in the potential models would enable this analysis to resolve the current discrepancy between experiment and theory.

We have obtained spectra of the high-lying vibrational levels of the

{1}^{3}

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

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

via photoassociation of ultracold

^{6}\mathrm{Li}

atoms confined in a magneto-optical trap. The

{1}^{3}

${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ state of the diatomic molecule correlates to a 2

{\mathit{S}}_{1/2}

state atom plus a 2

{\mathit{P}}_{1/2}

state atom. The long-range part of the molecular interaction potential for this state depends on the 2P atomic radiative lifetime. By calculating the energy eigenvalues of a model potential for the

{1}^{3}

${\mathrm{\ensuremath{\Sigma}}}_{\mathit{g}}^{+}$ state and fitting them to the experimentally measured vibrational levels, we have extracted a value for the 2P lifetime of 26.99\ifmmode\pm\else\textpm\fi{}0.16 ns. The precision is currently limited by the accuracy of a region of the model potential provided by ab initio calculations.

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.