Photoassociation experiments with ultracold metastable helium

Kim, J.; Rapol, U. D.; Moal, S.; Léonard, Jérémie; Walhout, M.; Leduc, Michèle

doi:10.1140/epjd/e2004-00144-9

Cited by 23 publications

(44 citation statements)

References 33 publications

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“…In this letter, we report the first observation of the light shift of the J=1 ro-vibrational states recently found by our group [12,13] in the purely long-range 0 + u interaction potential for 4 He atoms. The v=0, 1, 2 levels (see Fig.…”

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confidence: 66%

Frequency shifts of photoassociative spectra of ultracold metastable helium atoms: A new measurement of the s -wave scattering length

et al. 2005

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Abstract. -We observe light-induced frequency shifts in one-color photoassociative spectra of magnetically trapped 4 He * atoms in the metastable 2 3 S1 state. A pair of ultracold spinpolarized 2 3 S1 helium atoms is excited into a molecular bound state in the purely long range 0 + u potential connected to the 2 3 S1 −2 3 P0 asymptote. The shift arises from the optical coupling of the molecular excited bound state with the scattering states and the bound states of two colliding 2 3 S1 atoms. We measure the frequency-shifts for several ro-vibrational levels in the 0 + u potential and find a linear dependence on the photoassociation laser intensity. Comparison with a theoretical analysis provides a good indication for the s-wave scattering length a of the quintet ( 5 Σ + g ) potential, a = 7.2 ± 0.6 nm, which is significantly lower than most previous results obtained by non-spectroscopic methods.Introduction. -The present article describes a photoassociation (PA) experiment with ultracold helium atoms in the metastable (τ ∼ 8000 s) 2 3 S 1 state. Since the development of laser cooling techniques which provide sub-millikelvin ultracold atomic samples, the photoassociation of such atoms has been of much interest and provides detailed information on the inter-atomic interaction and collisional properties [1]. The measurement of the PA spectra allows very precise measurement of the s-wave scattering length [2-5], a crucial parameter for understanding the collisional properties of the ultracold atoms or molecules and the dynamic behavior of the condensate.One of the interesting phenomena in PA is the light induced frequency shift of the PA spectra. As demonstrated in Ref. [6,7] for Na and Ref. [8,9] for Li, the light shift of the PA spectra is clearly visible at moderate laser intensity for the ultracold samples. The observed shifts are described by a theoretical calculation based on the theory developed by Bohn and Julienne [10] or Simoni et al. [11]. The laser light couples the excited molecular bound state with the continuum of scattering states and the ground molecular bound states, which results in the shift of the PA resonance curve when the laser frequency is swept over the resonance. The dependance of the shift on a has two origins. First, in the limit of large and positive scattering length a, the energy of the least bound-state E LBS in the ground state potential

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confidence: 66%

Frequency shifts of photoassociative spectra of ultracold metastable helium atoms: A new measurement of the s -wave scattering length

et al. 2005

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“…We only consider the leading term C 9 (M, ±) of V (3) , which is comparable to the smallest term of V (2) .…”

Section: M) (25)mentioning

confidence: 99%

“…Recently, there has been considerable interest in the study of helium dimers and ultracold helium collisions associated with metastable helium atoms [1,2,3,4,5,6,7,8,9,10,11].…”

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Long-range interactions between aHe(2S3)atom and a

et al. 2006

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Long-range interactions between a He(2 3 S) atom and a He(2 3 P ) atom for like isotopes AbstractFor the interactions between a He(2 3 S) atom and a He(2 3 P ) atom for like isotopes, we report perturbation theoretic calculations using accurate variational wave functions in Hylleraas coordinates of the coefficients determining the potential energies at large internuclear separations. We evaluate the coefficient C 3 of the first order resonant dipole-dipole energy and the van der Waals coefficients C 6 , C 8 , and C 10 for the second order energies arising from the mutual perturbations of instantaneous electric dipole, quadrupole, and octupole interactions. We also evaluate the coefficient C 9 of the leading contribution to the third order energy. We establish definitive values including treatment of the finite nuclear mass for the 3 He(2 3 S)-3 He(2 3 P ) and 4 He(2 3 S)-4 He(2 3 P ) interactions.

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“…From these two experiments Moal et al [1] obtain the estimate 0.05 < γ g /2π < 0.3 MHz, corresponding to a lifetime τ g between 0.5 and 3 µs. The decay width is also needed in the interpretation of one-laser photoassociation experiments using calorimetric detection [4,5,6] as decay of the v = 14 bound state contributes to the heating of the trapped atoms. Koelemeij and Leduc [3] have given a theoretical estimate of τ g based upon the semiclassical vibration frequency of the v = 14 level and inelastic decay rates due to spin relaxation and relaxation-induced ionization [7,8].…”

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confidence: 99%

Spin-dipole-induced lifetime of the least-boundΣg+5state ofHe(2S
Beams
¹
,
Peach
²
,
Whittingham
³

2006
Phys. Rev. A
8
0
10
2
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The properties of the least-bound vibrational level (v = 14) of the 5 Σ + g state formed during the ultracold collision of two spin-polarized metastable 2 3 S1 helium atoms are crucial to studies of photoassociation spectroscopy of metastable helium. We report a calculation of the autoionization lifetime τg of this state induced by spin-dipole coupling of the 5 Σ + g state to the 1 Σ + g state from which Penning and associative ionization processes are highly probable. We find τg ≈ 150 µs, significantly larger than the recent experimental estimates of (4 − 5) µs.

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Photoassociation experiments with ultracold metastable helium

Cited by 23 publications

References 33 publications

Frequency shifts of photoassociative spectra of ultracold metastable helium atoms: A new measurement of the s -wave scattering length

Frequency shifts of photoassociative spectra of ultracold metastable helium atoms: A new measurement of the s -wave scattering length

Long-range interactions between aHe(2S3)atom and a

Spin-dipole-induced lifetime of the least-boundΣg+5state ofHe(2S
Beams
¹
,
Peach
²
,
Whittingham
³

2006
Phys. Rev. A
8
0
10
2
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Photoassociation experiments with ultracold metastable helium

Cited by 23 publications

References 33 publications

Frequency shifts of photoassociative spectra of ultracold metastable helium atoms: A new measurement of the s -wave scattering length

Frequency shifts of photoassociative spectra of ultracold metastable helium atoms: A new measurement of the s -wave scattering length

Long-range interactions between aHe(2S3)atom and a

Spin-dipole-induced lifetime of the least-boundΣg+5state ofHe(2SBeams1, Peach2, Whittingham3 2006Phys. Rev. A80102View full textAdd to dashboardCite

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Spin-dipole-induced lifetime of the least-boundΣg+5state ofHe(2S
Beams
¹
,
Peach
²
,
Whittingham
³

2006
Phys. Rev. A
8
0
10
2
View full text Add to dashboard Cite