Photoassociative spectroscopy of 1g, 0+u, and 0−g states of Na2

Ratliff, L P.; Wagshul, Mark E.; Lett, Paul D.; Rolston, S. L.; Phillips, William D.

doi:10.1063/1.467638

Cited by 101 publications

(45 citation statements)

References 17 publications

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“…Compared to the size of a ground diatomic molecule whose equilibrium position ranges in general between 2 and 10 Bohr radius, these 0 − g and 1 u molecular states are truly long ranged. The PA spectrum for some vibrational states of 0 − g of Na 2 have already been observed experimentally [25].…”

Section: The Model Systemmentioning

confidence: 69%

Model study on the photoassociation of a pair of trapped atoms into an ultralong-range molecule

Deb

You

2003

Phys. Rev. A

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Using the method of quantum-defect theory, we calculate the ultralong-range molecular vibrational states near the dissociation threshold of a diatomic molecular potential which asymptotically varies as −1/R 3 . The properties of these states are of considerable interest as they can be formed by photoassociation (PA) of two ground state atoms. The Franck-Condon overlap integrals between the harmonically trapped atom-pair states and the ultralong-range molecular vibrational states are estimated and compared with their values for a pair of untrapped free atoms in the low-energy scattering state. We find that the binding between a pair of ground-state atoms by a harmonic trap has significant effect on the Franck-Condon integrals and thus can be used to influence PA. Trapinduced binding between two ground-state atoms may facilitate coherent PA dynamics between the two atoms and the photoassociated diatomic molecule.

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Section: The Model Systemmentioning

confidence: 69%

Model study on the photoassociation of a pair of trapped atoms into an ultralong-range molecule

Deb

You

2003

Phys. Rev. A

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“…The structures in the production of ions as a function of the frequency of the exciting light in these experiments reflects the boundstate structure of the singly excited states ͑Na 2 ‫ء‬ ͒. The second step, which is a bound-free transition, displays no observable structure in these experiments [2][3][4][5][6]. The reaction mechanism at those low energies displays some characteristics different from those in the reaction mechanism at typical thermal temperatures.…”

Section: (Received 13 March 1996)mentioning

confidence: 85%

“…A number of groups has studied this reaction using only a single exciting laser for the two successive excitation steps [5,6]. Since the last step in this reaction is insensitive to the exciting laser frequency, they found that the production of ions as a function of frequency reflects the structure of the bound singly excited sates.…”

Section: (Received 13 March 1996)mentioning

confidence: 99%

“…Second, due to the attraction in this bound intermediate state the atoms are effectively accelerated to each other and reach the short internuclear distances where direct photoionization takes place. To distinguish this reaction from the associative ionization reaction this mechanism is referred to as photoassociative ionization (PAI).A number of groups has studied this reaction using only a single exciting laser for the two successive excitation steps [5,6]. Since the last step in this reaction is insensitive to the exciting laser frequency, they found that the production of ions as a function of frequency reflects the structure of the bound singly excited sates.…”

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confidence: 99%

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Long-Range Predissociation in Two-Color Photoassociation of Ultracold Na Atoms

1996

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We report two-color photoassociative ionization of sodium in a magneto-optical trap. The experimental results yield information on both singly and doubly excited states. We find that the highest bound vibrational levels (y . 20) of the singly excited 0 2 g state predissociate into the 3 2 P 3͞2 1 3 2 S 1͞2 ͑F g 1͒ dissociation continuum due to avoided crossings of the hyperfine components of this potential with other molecular symmetries. Based on symmetry and energy consideration we argue that a doubly excited 1 u state remains autoionizing even when excited only a few GHz above the dissociation continuum. [S0031-9007(96) PACS numbers: 33.80. Gj, 32.80.Pj, 33.15.Mt, 34.50.Rk The rapid development of laser cooling techniques (for a review see [1]) during the last decade has opened the path for study of cold collisions. The narrow thermal energy distribution in which the atoms can be prepared allows spectroscopy with extremely high resolution. One of the reactions that has been studied is the photoassociative ionization reaction for sodium (Na 1 Na 1hv ! Na 2 ‫ء‬ , followed by Na 2 ‫ء‬ 1hv ! Na 2 1 1 e 2 ). The structures in the production of ions as a function of the frequency of the exciting light in these experiments reflects the boundstate structure of the singly excited states ͑Na 2 ‫ء‬ ͒. The second step, which is a bound-free transition, displays no observable structure in these experiments [2][3][4][5][6]. The reaction mechanism at those low energies displays some characteristics different from those in the reaction mechanism at typical thermal temperatures. At thermal energies the associative ionization (AI) reaction involves two atoms prepared in excited states, which due to their thermal motion reach the reaction region where autoionization takes place. At temperatures that can be reached with laser cooling techniques the velocity of the excited atoms is so low (typically a few cm͞s) that they propagate only a few a 0 before they spontaneously emit a photon and decay to the ground state. So the colliding excited atom pair will not survive to the reaction region.Until now, the reaction at low temperature has been described as a three step process [5]. First, the two colliding atoms are excited at long range to a bound singly excited molecular state (Fig. 1). Second, due to the attraction in this bound intermediate state the atoms are effectively accelerated to each other and reach the short internuclear distances where direct photoionization takes place. To distinguish this reaction from the associative ionization reaction this mechanism is referred to as photoassociative ionization (PAI).A number of groups has studied this reaction using only a single exciting laser for the two successive excitation steps [5,6]. Since the last step in this reaction is insensitive to the exciting laser frequency, they found that the production of ions as a function of frequency reflects the structure of the bound singly excited sates. Unfortunately, this excitation scheme is restricted to those singly excited states...

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“…The PA transition to the 1 g level is weakly allowed by singlet-triplet mixing, but it still presents a relatively strong one-color ionization signal. This level has been the subject of many previous photoassociation studies [12,13,14,15,16]. The use of a weak transition allows the resolution of rotational levels at high intensities, which otherwise might be unresolved due to power broadening and state mixing.…”

Section: Methodsmentioning

confidence: 99%

Light forces in ultracold photoassociation

et al. 2007

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We study the time-resolved photoassociation of ultracold sodium in an optical dipole trap. The photoassociation laser excites pairs of atoms to molecular states of large total angular momentum at high intensities (above 20 kW/cm 2 ). Such transitions are generally suppressed at ultracold temperatures by the centrifugal barriers for high partial waves. Time-resolved ionization measurements reveal that the atoms are accelerated by the dipole potential of the photoassociation beam. We change the collision energy by varying the potential depth, and observe a strong variation of the photoassociation rate. These results demonstrate the important role of light forces in cw photoassociation at high intensities.

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Photoassociative spectroscopy of 1g, 0+u, and 0−g states of Na2

Abstract: We use photoassociation of ultracold Na to study transitions from free atoms to bound molecules. We obtain rovibrational spectra of the 1g, the 0+u, and, for the first time, the 0−g ‘‘purely long-range’’ state of Na2, all of which dissociate to Na(3 2S1/2)+Na(3 2P3/2).

Cited by 101 publications

References 17 publications

Model study on the photoassociation of a pair of trapped atoms into an ultralong-range molecule

Model study on the photoassociation of a pair of trapped atoms into an ultralong-range molecule

Long-Range Predissociation in Two-Color Photoassociation of Ultracold Na Atoms

Light forces in ultracold photoassociation

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