3Seand1Sescattering lengths for e-+ Rb, Cs and Fr collisions

Bahrim, Cristian; Thumm, Uwe; Fabrikant, I. I.

doi:10.1088/0953-4075/34/6/107

Cited by 61 publications

(65 citation statements)

References 16 publications

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“…(For 37D 5/2 the ν = 0 binding energy increases by about 4 MHz when changing a s0 from −13.5 to −14.5 a 0 .) This a s0 -value lies within the range of published values −13 to -19.48 a 0 [2,6,[20][21][22]. The experimental signals at about half the ν = 0 binding energies, seen in some of the plots in Fig.…”

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confidence: 81%

Photoassociation of Long-RangenDRydberg Molecules

2014

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We observe long-range homonuclear diatomic nD Rydberg molecules photoassociated out of an ultracold gas of 87 Rb atoms for 34≤ n ≤40. The measured ground-state binding energies of 87 Rb(nD − 5S 1/2 ) molecular states are larger than those of their 87 Rb(nS − 5S 1/2 ) counterparts, showing the dependence of the molecular bond on the angular momentum of the Rydberg atom. We exhibit the transition of 87 Rb(nD − 5S 1/2 ) molecules from a molecular-binding-dominant regime at low n to a fine-structure-dominant regime at high n [akin to Hund's cases (a) and (c), respectively]. In the analysis the fine structure of the nD Rydberg atom and the hyperfine structure of the 5S 1/2 atom are included.PACS numbers: 34.50. Cx,34.20.Cf,33.80.Rv,31.10.+z, Cold atomic systems have opened new frontiers at the interface of atomic and molecular physics. Of particular interest are a recently discovered class of long-range, homonuclear Rydberg molecules [1,2]. Formed via an attractive interaction between a Rydberg electron and a ground-state atom [1], these molecules are among the largest ever observed with internuclear separations of several thousand Bohr radii. Their distinctive binding mechanism, which is unlike conventional covalent, ionic, and van der Waals bonds between ground-state atoms, results in loosely bound molecules whose properties closely mimic those of their constituent Rydberg atoms. The discovery of these molecular bonds has been likened to a new ultracold chemistry [3], and has spurred a significant amount of theoretical [4,5] and experimental interest [6][7][8][9]. Non-degenerate, low angular momentum Rydberg states (orbital angular momentum ℓ ≤ 2 in rubidium) produce molecules with a few tens of MHz binding energies and permanent electric dipole moments of a few Debye. The ℓ = 0 molecules were first observed by photoassociation [10] The relevant interaction was first described by Fermi [11] to help explain pressure-induced energy shifts of Rydberg absorption lines in a gas [12]. The deBroglie wavelength of the Rydberg electron (position r) is much larger than that of a heavy ground-state atom (position R) that lies within the Rydberg atom's volume, and their interaction can be approximated as a low-energy s-wave scattering process (scattering length a s ). The interaction is described with a Fermi-type pseudopotential [1,13], V pseudo (r) = 2πa s δ 3 (r − R), where p-wave and higherorder scattering [4] are neglected. For negative a s the interaction can lead to bound molecular states [1,13].In the present work we focus on long-range 87 Rb 2 molecules formed by an nD Rydberg and a 5S 1/2 ground state atom. The binding energies generally increase with ℓ, due to the √ 2ℓ + 1-scaling of the Y m=0 l (θ = 0). Among the low-ℓ variety of these molecules the nD ones have the highest binding energies. The angular-momentum coupling spans three Hund's cases when varying ℓ from 0 to 2. The nS 1/2 − 5S 1/2 molecules are akin to Hund's case (b), because they have L = 0 and total electron spin S = 1. The nP j − 5S 1/2 molecules a...

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confidence: 81%

Photoassociation of Long-RangenDRydberg Molecules

2014

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“…The analysis of the experimental data confirmed the overall validity of Eq. (1), revealed contributions from triplet pwave scattering channels, and enabled the determination of triplet s-and p-wave scattering lengths that confirmed theoretical predictions [13].Singlet s-wave scattering lengths are expected to be either positive or much smaller than triplet scattering lengths [14,15] and thus scattering in singlet channels has not been included in the analysis of the experimental data. Anderson et al [16] have recently predicted that the hyperfine coupling in the ground-state atom should effectively mix triplet and singlet scattering channels and lead to shallow bound states in addition to the more strongly bound states resulting from pure triplet scattering.…”

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confidence: 61%

“…Fabrikant [14] and, more recently, Bahrim et al [15] calculated the e − -Cs s-wave scattering lengths to be a T,0 =−22.7 a 0 and a S,0 =−2.4 a 0 , and a T,0 =−21.7 a 0 and a S,0 =−1.33 a 0 , respectively, from an effective-rangetheory analysis of higher-energy scattering data. As measure of the deviation between experiment and theory, we consider the absolute error in the zero-energy scattering phase shift δ 0 =arctan (a i /R pol ) + π/4 [28], where R pol = √ α=20.05 a 0 is the typical range of the e − -Cs interaction and α is the polarizability of the Cs groundstate atom.…”

Section: Fig 2 Detected Csmentioning

confidence: 99%

“…Thus, only the shallow 1,3 Σ states correlating to the ns 1/2 ,5s 1/2 (F =2) asymptotes could have been observed. Using a triplet s-wave scattering length of a T,0 = −18.5a 0 [7] and the literature value for a S,0 = +0.627a 0 [15] we predict the positions of the v=0 levels of the n = 35−37 1,3 Σ shallow potential wells listed in the column E Th 2, 1,3 Σ of Tab. II.…”

Section: Fig 2 Detected Csmentioning

confidence: 99%

“…Singlet s-wave scattering lengths are expected to be either positive or much smaller than triplet scattering lengths [14,15] and thus scattering in singlet channels has not been included in the analysis of the experimental data. Anderson et al [16] have recently predicted that the hyperfine coupling in the ground-state atom should effectively mix triplet and singlet scattering channels and lead to shallow bound states in addition to the more strongly bound states resulting from pure triplet scattering.…”

mentioning

confidence: 99%

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Experimental Characterization of Singlet Scattering Channels in Long-Range Rydberg Molecules

2015

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We observe the formation of long-range Cs2 Rydberg molecules consisting of a Rydberg and a ground-state atom by photoassociation spectroscopy in an ultracold Cs gas near 6s 1/2 (F =3,4)→np 3/2 resonances (n=26-34). The spectra reveal two types of molecular states recently predicted by D. A. Anderson, S. A. Miller, and G. Raithel [Phys. Rev. A 90, 062518 (2014)]: states bound purely by triplet s-wave scattering with binding energies ranging from 400 MHz at n=26 to 80 MHz at n=34, and states bound by mixed singlet-triplet s-wave scattering with smaller and F -dependent binding energies. The experimental observations are accounted for by an effective Hamiltonian including s-wave scattering pseudopotentials, the hyperfine interaction of the ground-state atom, and the spin-orbit interaction of the Rydberg atom. The analysis enabled the characterization of the role of singlet scattering in the formation of long-range Rydberg molecules and the determination of an effective singlet s-wave scattering length for low-energy electron-Cs collisions.Atoms in Rydberg states of high principal quantum number n are weakly bound systems and are extremely sensitive to their environment. In 1934, Amaldi and Segrè [1] observed the pressure-dependent shift and broadening of the Rydberg series of alkali atoms in a gas cell, an effect which was explained by Fermi [2] as originating from the elastic scattering between slow Rydberg electrons and ground-state atoms within the Rydberg orbit. He modeled the pressure shift using a pseudopotentialwhere a is the scattering length and |Ψ(R)| 2 the probability density of the Rydberg electron at the position R of the neutral perturber. Measurements of pressure shifts in Rydberg states thus provide information on the cross sections of elastic collisions between slow electrons and atoms and molecules [2,3]. Equation (1) implies the existence of oscillating interaction potentials between Rydberg and ground-state atoms [4,5]. A manifestation of such potentials are long-range diatomic molecules in which a ground-state atom having a negative s-wave scattering length is attached to a Rydberg atom at a distance corresponding to an antinode of Ψ(R), as was first pointed out by Greene et al. [6]. Such molecules were first observed experimentally by Bendkowsky et al. [7] following excitation of Rb atoms close to ns 1/2 Rydberg states with n=35-37. Later investigations led to the detection of long-range Rb 2 molecules correlated to np 1/2,3/2 (n=7-12) [8], nd 3/2,5/2 (n=34-40) [9], and nd 3/2,5/2 (n=40-49) [10] dissociation asymptotes and long-range Cs 2 molecules correlated to ns 1/2 (n=31-34) [11] and ns 1/2 (n=37,39,40) [12] asymptotes. The analysis of the experimental data confirmed the overall validity of Eq. (1), revealed contributions from triplet pwave scattering channels, and enabled the determination of triplet s-and p-wave scattering lengths that confirmed theoretical predictions [13].Singlet s-wave scattering lengths are expected to be either positive or much smaller than triplet scattering length...

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Ultracold Rydberg Atom–Atom Interaction

Sadeghpour

2023

Springer Handbooks

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³S^eand¹S^escattering lengths for e^-+ Rb, Cs and Fr collisions

Cited by 61 publications

References 16 publications

Photoassociation of Long-RangenDRydberg Molecules

Photoassociation of Long-RangenDRydberg Molecules

Experimental Characterization of Singlet Scattering Channels in Long-Range Rydberg Molecules

Ultracold Rydberg Atom–Atom Interaction

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