Spin-dipole-induced lifetime of the least-boundΣg+5state ofHe(2S

Abstract

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.

Lifetime of weakly bound dimers of ultracold metastable helium studied by photoassociation

“…Their linewidths are interpreted in term of processes limiting the lifetime τ of the exotic molecule. A value of τ = 1.4 ± 0.3 µs is found, which significantly differs from two recent calculations of the Penning ionization rate induced by spin-dipole coupling [1,2]. The limitation of τ by atom-molecule inelastic collisions is investigated and ruled out.…”

Feshbach resonances inHe3*-Goosen1, Tiecke2, Vassen3 et al. 2010Phys. Rev. A142320View full textAdd to dashboardCite

“…[20]. The magnetic dipole-dipole interaction is thus treated as a perturbation in first order in the ABM, similar to the treatment of magnetic dipole-dipole interactions for metastable helium atoms by Beams et al [45].…”

“…Since these two bound states can be coupled by the V dd interaction, the S = 2, = 0 bound state will become less stable. This can be of interest to recent studies [45,46] on the lifetime of the S = 2, = 0 bound state of the C + C channel. This qualitative argument needs further investigation.…”

Laser-intensity dependence of photoassociation in ultracold metastable helium

“…We employ the F-operator technique [27,28] to evaluate δE (2) e . This approach has recently been used by Beams et al [29,30] to treat spin-dipole interactions as a perturbation and we adapt their formalism here to the laser-matter interaction Ĥint . The shift is given by…”