Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:cond-mat/0612324 · Physical Review A

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

Steven Moal, M. Portier, Nassim Zahzam, Michèle Leduc

Published Mar 26, 2007• 9 citations
arXivHTMLPDF

Abstract

We describe two-photon photoassociation (PA) experiments operated in an ultracold gas of metastable $^{4}\mathrm{He}^{*}$ atoms in the $2\phantom{\rule{0.2em}{0ex}}^{3}S_{1}$ state. Atom-molecule dark resonances as well as Raman signals provide information on the exotic molecule in the least bound vibrational $J=2$, $v=14$ state of the $^{5}\ensuremath{\Sigma}_{g}^{+}$ interaction potential of two spin-polarized metastable atoms. The physical origin of the various two-photon PA signals is first discussed. Their linewidths are interpreted in terms of processes limiting the lifetime $\ensuremath{\tau}$ of the exotic molecule. A value of $\ensuremath{\tau}=1.4\ifmmode\pm\else\textpm\fi{}0.3\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$ is found, which significantly differs from two recent calculations of the Penning ionization rate induced by spin-dipole coupling [T. J. Beams et al., Phys. Rev. A 74, 014702 (2006); M. Portier and G. V. Shlyapnikov (unpublished)]. The limitation of $\ensuremath{\tau}$ by atom-molecule inelastic collisions is investigated and ruled out.

DOI
10.1103/physreva.75.033415

Related papers

Spin-dipole-induced lifetime of the least-bound Σg+5 state of He(2S13)+He(2S13)

Timothy J. Beams, G. Peach, Ian B. Whittingham

The properties of the least-bound vibrational level $(v=14)$ of the $^{5}\ensuremath{\Sigma}_{g}^{+}$ state formed during the ultracold collision of two spin-polarized metastable $2\phantom{\rule{0.2em}{0ex}}^{3}S_{1}$ helium atoms are crucial to studies of photoassociation spectroscopy of metastable helium. We report a calculation of the autoionization lifetime ${\ensuremath{\tau}}_{g}$ of this state induced by spin-dipole coupling of the $^{5}\ensuremath{\Sigma}_{g}^{+}$ state to the $^{1}\ensuremath{\Sigma}_{g}^{+}$ state from which Penning and associative ionization processes are highly probable. We find ${\ensuremath{\tau}}_{g}\ensuremath{\approx}150\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$, significantly larger than the recent experimental estimates of $(0.5\ensuremath{-}3)\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$.

arXiv:physics/0604189•Physical Review A•Jul 18, 2006•8 citations

Accurate Determination of the Scattering Length of Metastable Helium Atoms Using Dark Resonances between Atoms and Exotic Molecules

Steven Moal, M. Portier, J. Kim +4 more

We present a new measurement of the $s$-wave scattering length $a$ of spin-polarized helium atoms in the $2\text{ }^{3}S_{1}$ metastable state. Using two-photon photoassociation spectroscopy and dark resonances, we measure the energy ${E}_{v=14}=\ensuremath{-}91.35\ifmmode\pm\else\textpm\fi{}0.06\text{ }\text{ }\mathrm{MHz}$ of the least-bound state $v=14$ in the interaction potential of the two atoms. We deduce a value of $a=7.512\ifmmode\pm\else\textpm\fi{}0.005\text{ }\text{ }\mathrm{nm}$, which is at least 100 times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of $1\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$.

arXiv:cond-mat/0509286•Physical Review Letters•Jan 20, 2006•92 citations

Analysis of photoassociation spectra for giant helium dimers

Jérémie Léonard, Allard P. Mosk, M. Walhout +3 more

We perform a theoretical analysis to interpret the spectra of purely long-range helium dimers produced by photoassociation (PA) in an ultracold gas of metastable helium atoms. The experimental spectrum obtained with the PA laser tuned closed to the $2\phantom{\rule{0.3em}{0ex}}^{3}S_{1}\ensuremath{\leftrightarrow}2\phantom{\rule{0.3em}{0ex}}^{3}P_{0}$ atomic line has been reported in a previous paper. Here, we first focus on the corrections to be applied to the measured resonance frequencies in order to infer the molecular binding energies. We then present a calculation of the vibrational spectra for the purely long-range molecular states, using adiabatic potentials obtained from perturbation theory. With retardation effects taken into account, the agreement between experimental and theoretical determinations of the spectrum for the ${0}_{u}^{+}$ purely long-range potential well is very good. The results yield a determination of the lifetime of the $2\phantom{\rule{0.3em}{0ex}}^{3}P$ atomic state.

arXiv:quant-ph/0310006•Physical Review A•Mar 5, 2004•27 citations

Spin-dipole-induced lifetime of the least-bound (5)Sigma(+)(g) state of He(2 S-3(1))+He(2 S-3(1))

Timothy J. Beams, G. Peach, I. B. Whittingham

The properties of the least-bound vibrational level (v=14) of the (5)Sigma(+)(g) state formed during the ultracold collision of two spin-polarized metastable 2 S-3(1) helium atoms are crucial to studies of photoassociation spectroscopy of metastable helium. We report a calculation of the autoionization lifetime tau(g) of this state induced by spin-dipole coupling of the (5)Sigma(+)(g) state to the (1)Sigma(+)(g) state from which Penning and associative ionization processes are highly probable. We find tau(g)approximate to 150 mu s, significantly larger than the recent experimental estimates of (0.5-3) mu s.

•Jul 1, 2006•0 citations

Photoassociation spectra and the validity of the dipole approximation for weakly bound dimers

Daniel Cocks, Ian B. Whittingham

Photoassociation (PA) of ultracold metastable helium to the $2s2p$ manifold is theoretically investigated using a nonperturbative close-coupled treatment in which the laser coupling is evaluated without assuming the dipole approximation. The results are compared with our previous study [D. G. Cocks and I. B. Whittingham, Phys. Rev. A 80, 023417 (2009)], which makes use of the dipole approximation. The approximation is found to strongly affect the PA spectra because the photoassociated levels are weakly bound, and a similar impact is predicted to occur in other systems of a weakly bound nature. The inclusion of the approximation does not affect the resonance positions or widths; however, significant differences are observed in the background of the spectra and the maximum laser intensity at which resonances are discernible. Couplings not satisfying the dipole selection rule $|J\ensuremath{-}1|\ensuremath{\leqslant}{J}^{\ensuremath{'}}\ensuremath{\leqslant}|J+1|$ do not lead to observable resonances.

arXiv:0912.4309•Physical Review A•Mar 8, 2010•1 citation

Ultracold collisions in metastable helium

G. Peach, Daniel Cocks, Ian B. Whittingham

Photoassociation processes are studied in ultracold collisions between different isotopes of metastable He(2 3 S) and He(2 3 P) atoms; Penning and associative ionization rates for collisions between two He(2 3 S) atoms are also obtained. Comparisons are made with data from existing experiments.

Journal of Physics Conference Series•Feb 1, 2017•3 citations
We describe two-photon photoassociation (PA) experiments operated in an ultracold gas of metastable 4He∗^{4}\mathrm{He}^{*}4He∗ atoms in the 23S12\phantom{\rule{0.2em}{0ex}}^{3}S_{1}23S1​ state. Atom-molecule dark resonances as well as Raman signals provide information on the exotic molecule in the least bound vibrational J=2J=2J=2, v=14v=14v=14 state of the 5\ensuremathΣg+^{5}\ensuremath{\Sigma}_{g}^{+}5\ensuremathΣg+​ interaction potential of two spin-polarized metastable atoms. The physical origin of the various two-photon PA signals is first discussed. Their linewidths are interpreted in terms of processes limiting the lifetime \ensuremathτ\ensuremath{\tau}\ensuremathτ of the exotic molecule. A value of \ensuremathτ=1.4\ifmmode±\else\textpm\fi0.3\ensuremathμs\ensuremath{\tau}=1.4\ifmmode\pm\else\textpm\fi{}0.3\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}\ensuremathτ=1.4\ifmmode±\else\textpm\fi0.3\ensuremathμs is found, which significantly differs from two recent calculations of the Penning ionization rate induced by spin-dipole coupling [T. J. Beams et al., Phys. Rev. A 74, 014702 (2006); M. Portier and G. V. Shlyapnikov (unpublished)]. The limitation of \ensuremathτ\ensuremath{\tau}\ensuremathτ by atom-molecule inelastic collisions is investigated and ruled out.
The properties of the least-bound vibrational level (v=14)(v=14)(v=14) of the $^{5}\ensuremath{\Sigma}_{g}^{+}$ state formed during the ultracold collision of two spin-polarized metastable 23S12\phantom{\rule{0.2em}{0ex}}^{3}S_{1}23S1​ helium atoms are crucial to studies of photoassociation spectroscopy of metastable helium. We report a calculation of the autoionization lifetime ${\ensuremath{\tau}}_{g}$ of this state induced by spin-dipole coupling of the $^{5}\ensuremath{\Sigma}_{g}^{+}$ state to the $^{1}\ensuremath{\Sigma}_{g}^{+}$ state from which Penning and associative ionization processes are highly probable. We find ${\ensuremath{\tau}}_{g}\ensuremath{\approx}150\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$, significantly larger than the recent experimental estimates of $(0.5\ensuremath{-}3)\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$.
We present a new measurement of the sss-wave scattering length aaa of spin-polarized helium atoms in the 2 3S12\text{ }^{3}S_{1}2 3S1​ metastable state. Using two-photon photoassociation spectroscopy and dark resonances, we measure the energy ${E}_{v=14}=\ensuremath{-}91.35\ifmmode\pm\else\textpm\fi{}0.06\text{ }\text{ }\mathrm{MHz}$ of the least-bound state v=14v=14v=14 in the interaction potential of the two atoms. We deduce a value of $a=7.512\ifmmode\pm\else\textpm\fi{}0.005\text{ }\text{ }\mathrm{nm}$, which is at least 100 times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of $1\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$.
We perform a theoretical analysis to interpret the spectra of purely long-range helium dimers produced by photoassociation (PA) in an ultracold gas of metastable helium atoms. The experimental spectrum obtained with the PA laser tuned closed to the $2\phantom{\rule{0.3em}{0ex}}^{3}S_{1}\ensuremath{\leftrightarrow}2\phantom{\rule{0.3em}{0ex}}^{3}P_{0}$ atomic line has been reported in a previous paper. Here, we first focus on the corrections to be applied to the measured resonance frequencies in order to infer the molecular binding energies. We then present a calculation of the vibrational spectra for the purely long-range molecular states, using adiabatic potentials obtained from perturbation theory. With retardation effects taken into account, the agreement between experimental and theoretical determinations of the spectrum for the 0u+{0}_{u}^{+}0u+​ purely long-range potential well is very good. The results yield a determination of the lifetime of the 23P2\phantom{\rule{0.3em}{0ex}}^{3}P23P atomic state.
The properties of the least-bound vibrational level (v=14) of the (5)Sigma(+)(g) state formed during the ultracold collision of two spin-polarized metastable 2 S-3(1) helium atoms are crucial to studies of photoassociation spectroscopy of metastable helium. We report a calculation of the autoionization lifetime tau(g) of this state induced by spin-dipole coupling of the (5)Sigma(+)(g) state to the (1)Sigma(+)(g) state from which Penning and associative ionization processes are highly probable. We find tau(g)approximate to 150 mu s, significantly larger than the recent experimental estimates of (0.5-3) mu s.
Photoassociation (PA) of ultracold metastable helium to the 2s2p2s2p2s2p manifold is theoretically investigated using a nonperturbative close-coupled treatment in which the laser coupling is evaluated without assuming the dipole approximation. The results are compared with our previous study [D. G. Cocks and I. B. Whittingham, Phys. Rev. A 80, 023417 (2009)], which makes use of the dipole approximation. The approximation is found to strongly affect the PA spectra because the photoassociated levels are weakly bound, and a similar impact is predicted to occur in other systems of a weakly bound nature. The inclusion of the approximation does not affect the resonance positions or widths; however, significant differences are observed in the background of the spectra and the maximum laser intensity at which resonances are discernible. Couplings not satisfying the dipole selection rule $|J\ensuremath{-}1|\ensuremath{\leqslant}{J}^{\ensuremath{'}}\ensuremath{\leqslant}|J+1|$ do not lead to observable resonances.