Physical Review A

Observation of the pure long-range 1u state of an alkali-metal dimer by photoassociative spectroscopy

Xiaotian Wang, He Wang, P. L. Gould, William C. Stwalley, Eite Tiesinga, Paul S. Julienne

Published Jun 1, 1998• 22 citations

Abstract

The pure long-range ${1}_{u}$ state of an alkali-metal dimer is observed in ${}^{39}{\mathrm{K}}_{2}$ using photoassociative spectroscopy of ultracold atoms. High-resolution spectra for vibrational levels $v=\stackrel{\ensuremath{\rightarrow}}{0}7$ are recorded by resonance-enhanced two-photon ionization. Strong rotation-hyperfine couplings are observed. Major molecular constants and a hyperfine structure analysis are presented. This ${1}_{u}$ state is useful as an ungerade Franck-Condon ``window'' at large internuclear distance for studies of highly excited long-range interactions.

DOI: 10.1103/physreva.57.4600

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Physical Review A

Observation of the pure long-range 1u state of an alkali-metal dimer by photoassociative spectroscopy

Xiaotian Wang, He Wang, P. L. Gould, William C. Stwalley, Eite Tiesinga, Paul S. Julienne

Published Jun 1, 1998• 22 citations

Publisher

Abstract

The pure long-range

{1}_{u}

state of an alkali-metal dimer is observed in

{}^{39}{\mathrm{K}}_{2}

using photoassociative spectroscopy of ultracold atoms. High-resolution spectra for vibrational levels

v=\stackrel{\ensuremath{\rightarrow}}{0}7

are recorded by resonance-enhanced two-photon ionization. Strong rotation-hyperfine couplings are observed. Major molecular constants and a hyperfine structure analysis are presented. This

{1}_{u}

state is useful as an ungerade Franck-Condon ``window'' at large internuclear distance for studies of highly excited long-range interactions.

DOI: 10.1103/physreva.57.4600

Related papers

Ultracold photoassociative spectroscopy of heteronuclear alkali-metal diatomic molecules

He Wang, William C. Stwalley

We have examined and identified the excited long-range Hund’s case (c) molecular states of the ten heteronuclear alkali metal diatomic molecules which support bound states and can be probed by ultracold photoassociative spectroscopy. Analytical expressions for the heteronuclear long-range free-bound Franck–Condon factors as a function of the internuclear distance R and the vibrational quantum number v are derived and discussed. The KRb system has considerably stronger excited long-range interactions than any other heteronuclear alkali diatomic molecule and has very favorable Franck–Condon factors for the photoassociation process. The heteronuclear photoassociative spectroscopy will provide spectroscopic measurements of the binary elastic scattering lengths of heteronuclear cold collisions which are the crucial parameters for sympathetic cooling of mixed atomic gases.We have examined and identified the excited long-range Hund’s case (c) molecular states of the ten heteronuclear alkali metal diatomic molecules which support bound states and can be probed by ultracold photoassociative spectroscopy. Analytical expressions for the heteronuclear long-range free-bound Franck–Condon factors as a function of the internuclear distance R and the vibrational quantum number v are derived and discussed. The KRb system has considerably stronger excited long-range interactions than any other heteronuclear alkali diatomic molecule and has very favorable Franck–Condon factors for the photoassociation process. The heteronuclear photoassociative spectroscopy will provide spectroscopic measurements of the binary elastic scattering lengths of heteronuclear cold collisions which are the crucial parameters for sympathetic cooling of mixed atomic gases.

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Photoassociative spectroscopy of highly excited vibrational levels of alkali-metal dimers: Green-function approach for eigenvalue solvers

Eite Tiesinga, Carl J. Williams, Paul S. Julienne

Understanding high-precision photoassociative spectroscopy of laser-cooled alkali-metal atoms involves modeling an extremely dense level structure of weakly bound molecules in the region where coriolis and hyperfine interactions become comparable to electronic interactions. We describe an iterative eigenvalue solver suitable for resolving these bound states that is based on finding eigenvalues of the shifted inverse or Green-function operator. Nonlinear coordinate transformations applied to the nuclear motion are introduced to minimize the dimensionality of the discretized Hamiltonian. The formalism is applied to resolve the hyperfine structure of rovibrational levels of the $\mathrm{Na}{(}^{2}P)+\mathrm{Na}{(}^{2}S)$ dimer.Understanding high-precision photoassociative spectroscopy of laser-cooled alkali-metal atoms involves modeling an extremely dense level structure of weakly bound molecules in the region where coriolis and hyperfine interactions become comparable to electronic interactions. We describe an iterative eigenvalue solver suitable for resolving these bound states that is based on finding eigenvalues of the shifted inverse or Green-function operator. Nonlinear coordinate transformations applied to the nuclear motion are introduced to minimize the dimensionality of the discretized Hamiltonian. The formalism is applied to resolve the hyperfine structure of rovibrational levels of the $\mathrm{Na}{(}^{2}P)+\mathrm{Na}{(}^{2}S)$ dimer.

Physical Review AJun 1, 199874 citations

PHOTOASSOCIATION OF ULTRACOLD ATOMS: A NEW TOOL FOR MOLECULAR SPECTROSCOPY

William C. Stwalley

The field of laser cooling and trapping of atoms has had a profound impact on many areas of atomic, molecular and optical science. In particular, ultracold atoms colliding in magneto-optical traps typically have relative kinetic energies of $300\\mu K (\\sim 7 MHz)$ , so free-bound absorption lines are as sharp as bound-bound lines. Moreover, because of very long range centrifugal barriers, only a few collisional partial waves are important ( $J^{\\prime\\prime} = 0, 1$ and 2 in our work on $^{39}K$ ). Such photoassociative free-bound absorption allows observation of ``pure long-range molecule'' states ( $R_{e} = 28$ and 39 {\\AA} in $^{39}K_{2}$ ) as well as long-range levels of known short range states with outer classical turning points of $\\sim 20 - 250 {\\AA}$ . Such spectra have been observed by ``trap loss'' (decrease in atomic fluorescence), molecular ionization, and fragment ionization. Optical-optical double resonance (OODR), e.g. through the ``Franck-Condon windows'' of the ``pure long-range'' states, produces readily assignable spectra at higher asymptotes as well. Further extensions of ultracold photoassociative spectroscopy and applications to determination of long range potentials, atomic properties, and Bose-Einstein condensate stability will be presented.The field of laser cooling and trapping of atoms has had a profound impact on many areas of atomic, molecular and optical science. In particular, ultracold atoms colliding in magneto-optical traps typically have relative kinetic energies of $300\\mu K (\\sim 7 MHz)$, so free-bound absorption lines are as sharp as bound-bound lines. Moreover, because of very long range centrifugal barriers, only a few collisional partial waves are important ($J^{\\prime\\prime} = 0, 1$ and 2 in our work on $^{39}K$). Such photoassociative free-bound absorption allows observation of ``pure long-range molecule'' states ($R_{e} = 28$ and 39 {\\AA} in $^{39}K_{2}$) as well as long-range levels of known short range states with outer classical turning points of $\\sim 20 - 250 {\\AA}$. Such spectra have been observed by ``trap loss'' (decrease in atomic fluorescence), molecular ionization, and fragment ionization. Optical-optical double resonance (OODR), e.g. through the ``Franck-Condon windows'' of the ``pure long-range'' states, produces readily assignable spectra at higher asymptotes as well. Further extensions of ultracold photoassociative spectroscopy and applications to determination of long range potentials, atomic properties, and Bose-Einstein condensate stability will be presented.

Jan 1, 19980 citations

The pure long-range

{1}_{u}

state of an alkali-metal dimer is observed in

{}^{39}{\mathrm{K}}_{2}

using photoassociative spectroscopy of ultracold atoms. High-resolution spectra for vibrational levels

v=\stackrel{\ensuremath{\rightarrow}}{0}7

are recorded by resonance-enhanced two-photon ionization. Strong rotation-hyperfine couplings are observed. Major molecular constants and a hyperfine structure analysis are presented. This

{1}_{u}

state is useful as an ungerade Franck-Condon ``window'' at large internuclear distance for studies of highly excited long-range interactions.

We report the first observation of optical-optical double resonance photoassociative spectroscopy of ultracold

{}^{39}

K atoms near the highly excited

^{39}K(4s)+^{39}K(4d,5d,6d,6s,7s)

asymptotes in a high density magneto-optical trap. Using the ${v}^{\ensuremath{'}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ level of the ${0}_{g}^{\ensuremath{-}}$ ``pure long-range'' state (a localized long-range Franck-Condon window) as the intermediate state, we observe simple and assignable rovibrational progressions dissociating to these asymptotes. The dominant long-range potential constants are determined. Line broadening, presumably due to autoionization, and rotational excitations due to strong field effects are observed.

\mathrm{Na}{(}^{2}P)+\mathrm{Na}{(}^{2}S)

dimer.

300\\mu K (\\sim 7 MHz)

, so free-bound absorption lines are as sharp as bound-bound lines. Moreover, because of very long range centrifugal barriers, only a few collisional partial waves are important (

J^{\\prime\\prime} = 0, 1

and 2 in our work on

^{39}K

). Such photoassociative free-bound absorption allows observation of ``pure long-range molecule'' states (

R_{e} = 28

and 39 {\\AA} in

^{39}K_{2}

) as well as long-range levels of known short range states with outer classical turning points of

\\sim 20 - 250 {\\AA}

. Such spectra have been observed by ``trap loss'' (decrease in atomic fluorescence), molecular ionization, and fragment ionization. Optical-optical double resonance (OODR), e.g. through the ``Franck-Condon windows'' of the ``pure long-range'' states, produces readily assignable spectra at higher asymptotes as well. Further extensions of ultracold photoassociative spectroscopy and applications to determination of long range potentials, atomic properties, and Bose-Einstein condensate stability will be presented.