Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physics World

Lasers probe long-range molecular states

Keith R. Burnett

Published Apr 1, 1997• 3 citations
Publisher

Abstract

Our ability to study the interactions between atoms at ultracold temperatures has undergone little short of a revolution in recent years. This is largely due to the development of spectroscopic techniques that can probe the properties of laser-cooled atoms with high precision. One of these techniques is photoassociation, and a group at the National Institute of Standards and Technology (NIST) in Maryland, US, has now used this method to obtain new information about the interactions between atoms in molecules. The NIST researchers used lasers to produce and probe pairs of sodium atoms that were bound together in very long-range molecular states (K M Jones et al. 1997 J. Phys. B.30289).

DOI
10.1088/2058-7058/10/4/23

Related papers

Photoassociative Spectroscopy of Laser-Cooled Atoms

Paul D. Lett, Paul S. Julienne, William D. Phillips

Advances in laser cooling of neutral atoms have made possible a new form of high-resolution laser spectroscopy: photoassociation of ultracold atoms. Colliding neutral atoms, confined in a laser trap, are photoassociated to bound excited states of the dimer molecule by absorbing a photon from a tunable laser. The technique can probe long range and “purely long range” molecular states that are difficult or impossible to detect by traditional means and, because of the extremely low energy of the colliding atoms (<1 mK), is capable of high resolution (<0.001 cm-1). The spectra are useful for atomic lifetime measurements, determination of atomic ground-state scattering information, and measurement of curve-crossing probabilities. Theoretical and experimental work in the field, including multiple resonance techniques and photo association line shapes, are reviewed.

Annual Review of Physical Chemistry•Jan 1, 1995•146 citations

Ultracold photoassociation spectroscopy: Long-range molecules and atomic scattering

K. M. Jones, Eite Tiesinga, Paul D. Lett +1 more

Photoassociation is the process in which two colliding atoms absorb a photon to form an excited molecule. The development of laser-cooling techniques for producing gases at ultracold $(<1\phantom{\rule{0.3em}{0ex}}\mathrm{mK})$ temperatures allows photoassociation spectroscopy to be performed with very high spectral resolution. Of particular interest is the investigation of molecular states whose properties can be related, with high precision, to the properties of their constituent atoms with the ``complications'' of chemical binding accounted for by a few parameters. These include bound long-range or purely long-range vibrational states in which two atoms spend most or all of their time at large internuclear separations. Low-energy atomic scattering states also share this characteristic. Photoassociation techniques have made important contributions to the study of all of these. This review describes what is special about photoassociation spectroscopy at ultracold temperatures, how it is performed, and a sampling of results including the determination of scattering lengths, their control via optical Feshbach resonances, precision determinations of atomic lifetimes from molecular spectra, limits on photoassociation rates in a Bose-Einstein condensate, and briefly, production of cold molecules. Discussions are illustrated with examples on alkali-metal atoms as well as other species. Progress in the field is already past the point where this review can be exhaustive, but an introduction is provided on the capabilities of photoassociation spectroscopy and the techniques presently in use.

Reviews of Modern Physics•May 22, 2006•873 citations

Collisions and photoionization of laser-cooled atoms: When atoms go bump in the light

L. P. Ratliff

Advances in laser cooling of neutral atoms have made possible a new form of high resolution spectoscopy: photoassociation of ultracold atoms. Colliding neutral atoms, confined in a laser trap, are photoassociated to bound excited states of the dimer molecule by absorbing a photon from a tunable laser. The technique can probe long range and {open_quote}purely long range{close_quote} molecular states that are difficult or impossible to detect by traditional means and, because of the extremely low energy of the colliding atoms (1 mK), is capable of high resolution (0.001 cm{minus}1). Recent results include, the first direct (and most precise) measurement of a molecular dissociation limit, the first observation of retardation effects in atom-atom interactions, high precision measurements of atomic lifetimes, and the study of exotic states of alkali dimers.

Bulletin of the American Physical Society•May 1, 1996•0 citations

High-resolution photoassociation spectroscopy

Joseph D. Miller, Robert A. Cline, D. J. Han +1 more

With the ultracold temperatures (T 1012 cm-3) of atoms that can be produced with laser-cooling and trapping techniques, it is now possible to carry out a new kind of high-resolution spectroscopy.1 This photoassociation is based on optical absorption resonances between the initially free states of colliding atoms and specific, bound excited molecular states. High resolution can be obtained because of the narrow energy distribution of the ultracold gas.1 Because the initial states are formed by collisions, it becomes possible to probe unique, excited molecular states with very large interatomic separations that are impossible to probe with conventional molecular spectroscopy. The feasibility of this new spectroscopy has been demonstrated in two recent experiments.2,3

•May 8, 1994•0 citations

Photoassociative ionization spectroscopy in ultracold sodium

Paul D. Lett, L. P. Ratliff, Mark E. Wagshul +2 more

Recent advances in laser cooling techniques have made possible a new type of spectroscopy. In the first experiments of this kind alkali atoms are laser cooled to temperatures around 1 mK and trapped, using laser fields, at densities around 1011 cm−3. Atoms colliding under such ultracold conditions can be resonantly photoassociated to bound states of the dimer molecules. These molecules can in turn be photoionized, providing a sensitive detection of the photoassociation spectrum and revealing in extremely high resolution the structure of the dimer molecules. The particular advantages of this technique include high resolution and signal‐to‐noise and the ability to reach extremely long range states of the molecule, accessible only through such slow collisions.

AIP conference proceedings•Jan 1, 1995•1 citation

Spectroscopy of Na2 by photoassociation of laser cooled Na

L. P. Ratliff, Mark E. Wagshul, Paul D. Lett +2 more

Recently, several groups,1-4 have used photoassociation of ultracold atoms to study transitions from free atoms to bound molecules. Photoassociative spectroscopy involves illuminating a collection of laser cooled and trapped atoms with a tunable probe laser. When the probe laser is resonant with transition to an excited molecular state, molecules are formed and detected either by ionizing the molecules or by monitoring changes in the number of trapped atoms.

•May 8, 1994•4 citations
Our ability to study the interactions between atoms at ultracold temperatures has undergone little short of a revolution in recent years. This is largely due to the development of spectroscopic techniques that can probe the properties of laser-cooled atoms with high precision. One of these techniques is photoassociation, and a group at the National Institute of Standards and Technology (NIST) in Maryland, US, has now used this method to obtain new information about the interactions between atoms in molecules. The NIST researchers used lasers to produce and probe pairs of sodium atoms that were bound together in very long-range molecular states (K M Jones et al. 1997 J. Phys. B.30289).
Advances in laser cooling of neutral atoms have made possible a new form of high-resolution laser spectroscopy: photoassociation of ultracold atoms. Colliding neutral atoms, confined in a laser trap, are photoassociated to bound excited states of the dimer molecule by absorbing a photon from a tunable laser. The technique can probe long range and “purely long range” molecular states that are difficult or impossible to detect by traditional means and, because of the extremely low energy of the colliding atoms (<1 mK), is capable of high resolution (<0.001 cm-1). The spectra are useful for atomic lifetime measurements, determination of atomic ground-state scattering information, and measurement of curve-crossing probabilities. Theoretical and experimental work in the field, including multiple resonance techniques and photo association line shapes, are reviewed.
Photoassociation is the process in which two colliding atoms absorb a photon to form an excited molecule. The development of laser-cooling techniques for producing gases at ultracold (<1mK)(<1\phantom{\rule{0.3em}{0ex}}\mathrm{mK})(<1mK) temperatures allows photoassociation spectroscopy to be performed with very high spectral resolution. Of particular interest is the investigation of molecular states whose properties can be related, with high precision, to the properties of their constituent atoms with the ``complications'' of chemical binding accounted for by a few parameters. These include bound long-range or purely long-range vibrational states in which two atoms spend most or all of their time at large internuclear separations. Low-energy atomic scattering states also share this characteristic. Photoassociation techniques have made important contributions to the study of all of these. This review describes what is special about photoassociation spectroscopy at ultracold temperatures, how it is performed, and a sampling of results including the determination of scattering lengths, their control via optical Feshbach resonances, precision determinations of atomic lifetimes from molecular spectra, limits on photoassociation rates in a Bose-Einstein condensate, and briefly, production of cold molecules. Discussions are illustrated with examples on alkali-metal atoms as well as other species. Progress in the field is already past the point where this review can be exhaustive, but an introduction is provided on the capabilities of photoassociation spectroscopy and the techniques presently in use.
Advances in laser cooling of neutral atoms have made possible a new form of high resolution spectoscopy: photoassociation of ultracold atoms. Colliding neutral atoms, confined in a laser trap, are photoassociated to bound excited states of the dimer molecule by absorbing a photon from a tunable laser. The technique can probe long range and {open_quote}purely long range{close_quote} molecular states that are difficult or impossible to detect by traditional means and, because of the extremely low energy of the colliding atoms (1 mK), is capable of high resolution (0.001 cm{minus}1). Recent results include, the first direct (and most precise) measurement of a molecular dissociation limit, the first observation of retardation effects in atom-atom interactions, high precision measurements of atomic lifetimes, and the study of exotic states of alkali dimers.
With the ultracold temperatures (T 1012 cm-3) of atoms that can be produced with laser-cooling and trapping techniques, it is now possible to carry out a new kind of high-resolution spectroscopy.1 This photoassociation is based on optical absorption resonances between the initially free states of colliding atoms and specific, bound excited molecular states. High resolution can be obtained because of the narrow energy distribution of the ultracold gas.1 Because the initial states are formed by collisions, it becomes possible to probe unique, excited molecular states with very large interatomic separations that are impossible to probe with conventional molecular spectroscopy. The feasibility of this new spectroscopy has been demonstrated in two recent experiments.2,3
Recent advances in laser cooling techniques have made possible a new type of spectroscopy. In the first experiments of this kind alkali atoms are laser cooled to temperatures around 1 mK and trapped, using laser fields, at densities around 1011 cm−3. Atoms colliding under such ultracold conditions can be resonantly photoassociated to bound states of the dimer molecules. These molecules can in turn be photoionized, providing a sensitive detection of the photoassociation spectrum and revealing in extremely high resolution the structure of the dimer molecules. The particular advantages of this technique include high resolution and signal‐to‐noise and the ability to reach extremely long range states of the molecule, accessible only through such slow collisions.