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

Physical Review Letters

Excited-Ion Lifetimes Using Penning-Ionizing Collisions

W. F. Parks, L. D. Schearer

Published Aug 28, 1972• 11 citations
Publisher

Abstract

We show that in the Penning-ionizing collision $\mathrm{He}({2}^{3}{S}_{1})+X\ensuremath{\rightarrow}\mathrm{He}({1}^{1}{S}_{0})+{({X}^{+})}^{*}+e$ the precession of the ${\mathrm{He}}^{m}$ spin at its Larmor frequency forces the $J$ polarization of the Penning ion to rotate at the same frequency but shifted in phase. The tangent of the phase shift is proportional to the lifetime of the ionic state and presents a unique method for measuring excited-ion lifetimes.

DOI
10.1103/physrevlett.29.531

Related papers

Coherence Transfer in a Penning Ionizing Collision

L. D. Schearer, L. A. Riseberg

Modulation of the intensity of light emitted by ${\mathrm{Sr}}^{+}(^{2}P_{\frac{3}{2}})$ ions at the resonance frequency of metastable helium atoms has been observed, demonstrating that coherence has been transferred in the Penning collision. The coherent excitation of the Penning ions suggests that the techniques of "coherence spectroscopy" such as level-crossing and Hanle experiments can be extended to excited states of Penning ions which are currently inaccessible by means of optical excitation.

Physical Review Letters•Mar 15, 1971•24 citations

Étude d'une méthode de mesure de durées de vie de niveaux excités d'ions utilisant le transfert d'orientation lors de collisions de Penning

J. Hamel, J.P. Barrat

Nous décrivons une méthode permettant de mesurer la durée de vie des niveaux d'énergie d'ions par transfert de cohérence dans une collision de Penning contre des atomes d'hélium dans le niveau 2 3S1 initialement orienté. Si l'on soumet les atomes d'hélium dans le niveau 23S 1 à une résonance magnétique, le champ R.F. fait apparaître une composante transversale du moment magnétique des atomes métastables d'hélium, qui précesse de façon cohérente à la pulsation ω du champ R.F. L'orientation transversale de l'hélium est partiellement transférée aux ions produits lors de la collision de Penning. Après la collision elle précesse à la pulsation de Larmor ω' 0 du niveau excité dans lequel l'ion a été porté. Le taux d'orientation stationnaire du niveau excité de l'ion dépend du déphasage moyen, pendant la durée de vie τ' de ce niveau, entre la précession de Larmor à la pulsation ω' 0 et la précession forcée de l'hélium. On détecte l'orientation en mesurant le taux de modulation de la lumière émise par les ions lors de la désexcitation radiative du niveau excité considéré. L'étude de la variation de ce taux, en fonction de la pulsation ω de la radiofréquence, permet de mesurer la durée de vie τ'.

Journal de physique•Jan 1, 1978•2 citations

Collision measurements and excited-level lifetime measurements on ions stored in Paul, Penning and Kingdon ion traps

D. A. Church

Physics Reports•Jun 1, 1993•72 citations

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

Optical pumping in a flowing helium afterglow with additive metal impurity atoms

L. D. Schearer

It is demonstrated that in a Penning collision of optically oriented metastable helium atoms with an impurity metal atom such as barium, both the longitudinal and transverse components of spin angular momentum are conserved. This results in a polarization of the ion which may be detected by optical emission in the case of excited ion levels or absorption for the ground states. A series of experiments is described which demonstrates the spin dependence of the Penning-collision process. The magnetic resonance of excited-state ions may be observed directly; from the resonance-linewidth radiative lifetimes may be measured.

Physical Review A•Oct 1, 1974•25 citations

Ion Polarization Via Penning Collisions with Optically Pumped Metastable Helium

L. D. Schearer

Transfer of spin polarization from optically pumped metastable helium atoms to the ions of Cd, Sr, and Zn following Penning collisions has been demonstrated indicating that a component of spin angular momentum is conserved. The ion polarization, detected optically, exceeds 10% at ion concentrations on the order of ${10}^{10}$-${10}^{11}$ ${\mathrm{cm}}^{\ensuremath{-}3}$.

Physical Review Letters•Mar 31, 1969•49 citations
We show that in the Penning-ionizing collision He(23S1)+X\ensuremath→He(11S0)+(X+)∗+e\mathrm{He}({2}^{3}{S}_{1})+X\ensuremath{\rightarrow}\mathrm{He}({1}^{1}{S}_{0})+{({X}^{+})}^{*}+eHe(23S1​)+X\ensuremath→He(11S0​)+(X+)∗+e the precession of the Hem{\mathrm{He}}^{m}Hem spin at its Larmor frequency forces the JJJ polarization of the Penning ion to rotate at the same frequency but shifted in phase. The tangent of the phase shift is proportional to the lifetime of the ionic state and presents a unique method for measuring excited-ion lifetimes.
Modulation of the intensity of light emitted by Sr+(2P32){\mathrm{Sr}}^{+}(^{2}P_{\frac{3}{2}})Sr+(2P23​​) ions at the resonance frequency of metastable helium atoms has been observed, demonstrating that coherence has been transferred in the Penning collision. The coherent excitation of the Penning ions suggests that the techniques of "coherence spectroscopy" such as level-crossing and Hanle experiments can be extended to excited states of Penning ions which are currently inaccessible by means of optical excitation.
Nous décrivons une méthode permettant de mesurer la durée de vie des niveaux d'énergie d'ions par transfert de cohérence dans une collision de Penning contre des atomes d'hélium dans le niveau 2 3S1 initialement orienté. Si l'on soumet les atomes d'hélium dans le niveau 23S 1 à une résonance magnétique, le champ R.F. fait apparaître une composante transversale du moment magnétique des atomes métastables d'hélium, qui précesse de façon cohérente à la pulsation ω du champ R.F. L'orientation transversale de l'hélium est partiellement transférée aux ions produits lors de la collision de Penning. Après la collision elle précesse à la pulsation de Larmor ω' 0 du niveau excité dans lequel l'ion a été porté. Le taux d'orientation stationnaire du niveau excité de l'ion dépend du déphasage moyen, pendant la durée de vie τ' de ce niveau, entre la précession de Larmor à la pulsation ω' 0 et la précession forcée de l'hélium. On détecte l'orientation en mesurant le taux de modulation de la lumière émise par les ions lors de la désexcitation radiative du niveau excité considéré. L'étude de la variation de ce taux, en fonction de la pulsation ω de la radiofréquence, permet de mesurer la durée de vie τ'.
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 $(0.5\ensuremath{-}3)\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$.
It is demonstrated that in a Penning collision of optically oriented metastable helium atoms with an impurity metal atom such as barium, both the longitudinal and transverse components of spin angular momentum are conserved. This results in a polarization of the ion which may be detected by optical emission in the case of excited ion levels or absorption for the ground states. A series of experiments is described which demonstrates the spin dependence of the Penning-collision process. The magnetic resonance of excited-state ions may be observed directly; from the resonance-linewidth radiative lifetimes may be measured.
Transfer of spin polarization from optically pumped metastable helium atoms to the ions of Cd, Sr, and Zn following Penning collisions has been demonstrated indicating that a component of spin angular momentum is conserved. The ion polarization, detected optically, exceeds 10% at ion concentrations on the order of 1010{10}^{10}1010-1011{10}^{11}1011 ${\mathrm{cm}}^{\ensuremath{-}3}$.