C1Σ+, A1Σ+, and

Ian Stevenson

¹

,

David Blasing

²

,

Yong P. Chen

³

et al.

Abstract

We present the first spectroscopic studies of the C 1 Σ + electronic state and the A 1 Σ +-b 3 Π 0 + complex in 7 Li-85 Rb. Using resonantly-enhanced, two-photon ionization, we observed v = 7, 9, 12, 13 and 26 − 45 of the C 1 Σ + state. We augment the REMPI data with a form of depletion spectra in regions of dense spectral lines. The A 1 Σ +-b 3 Π 0 + complex was observed with depletion spectroscopy, depleting to vibrational levels v = 0 → 29 of the A 1 Σ + state and v = 8 → 18 of the b 3 Π 0 + state. For all three series, we determine the term energy and vibrational constants. Finally, we outline several possible future projects based on the data presented here.

Microwave coherent control of ultracold ground-state molecules formed by short-range photoassociation

“…In particular, short-range photoassociation offers a simple optical pathway from atoms to molecules; it allows accumulation of cold molecules in the vibronic ground state, and can be applied to systems that are not amenable to magnetoassociation. Short-range PA has been implemented for various heteronuclear molecules [28][29][30][31][32] . We have recently formed polar 85 RbCs molecules in this way, trapped them optically, and measured atom-molecule collision rates 33 ) I n t e r n u c l e a r s e p a r a t i o n R ( Å ) lowed microwave (MW) transitions between neighbouring rotational states 35 , which may be driven with very high resolution.…”

Two-photon photoassociation spectroscopy of an ultracold heteronuclear molecule

“…There has been immense interest and progress in creating ultracold heteronuclear polar molecules [1][2][3][4][5][6][7][8][9][10][11][12] which, by virtue of their permanent electric dipole moment in the electronic ground state, are important for a variety of experiments not possible with ultracold atoms [13][14][15][16]. One-photon photoassociation (PA) of ultracold atoms [17] has been extensively used to create ultracold diatomic molecules in excited electronic states [12] and in many cases such molecules spontaneously decay to the electronic ground state [3,[18][19][20][21][22]. While this has been a successful strategy even for the formation of rovibronic ground state i.e.…”

“…While this has been a successful strategy even for the formation of rovibronic ground state i.e. X 1 Σ + ( = 0) molecules of some species [3,20,21], the process always leads to molecules being formed in a distribution of vibrational and rotational states [18][19][20][21][22]. An alternative approach is to again start with ultracold atoms but use a coherent coupling scheme for the formation of molecules in a specific rovibronic state.…”

“…We also calculated the efficiency for transfer to the X 1 Σ + ( = 43) level which has a binding energy of 137 cm -1 and a permanent electric dipole moment of ~1.5 Debye [34]. With the same laser powers and pulse sequence, but using as intermediate the B 1 Π ( = 20) level [35,51], located 125 GHz below the 7 Li (2s 2 S 1/2 ) + 85 Rb (5p 2 P 1/2 ) asymptote [22], we find a transfer efficiency of 1.7% that corresponds to 1.7 × 10 4 molecules in a single rovibrational X 1 Σ + ( = 43) level, starting with ~10 6 atoms. Such high efficiency is encouraging for all-optical production of ultracold molecules.…”

Optical shielding of destructive chemical reactions between ultracold ground-state NaRb molecules

“…In order to be implemented in future experiments, the present proposal now requires the spectroscopic characterization of the X 1 Σ + (v X = 0, j X = 0) → b 3 Π 0 (v b = 0, j b = 1) transition, namely its wavelength and its oscillator strength. While the X − b electronic transition has been experimentally studied for several species (LiRb [52], LiCs [53,54], NaK [55], NaRb [38], NaCs [56], KRb [57], KCs [58], RbCs [59]), these investigations are all performed at room temperatures, so that the rovibrational level (v X = 0, j X = 0) is not populated. Furthermore the forbidden character of the transition still needs to be carefully analyzed, which will be done in a forthcoming study.…”