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

Proceedings of the Physical Society

Properties of the Metastable Helium Atoms

A. Dalgarno, A E Kingston

Published Dec 1, 1958• 82 citations
Publisher

Abstract

The available theoretical values of the oscillator strengths of dipole transitions from each of the metastable states of helium are modified so that each set satisfies four different sum rules. They are then employed to evaluate the polarizabilities, the diamagnetic susceptibilities, the average energy losses for fast particle impact, the Lamb shift average excitation energies and the van der Waals interactions between normal and metastable helium atoms.

DOI
10.1088/0370-1328/72/6/314

Related papers

Polarizabilities of 3P Atoms and van der Waals Coefficients for Their Interaction with Helium Atoms

Xi Chu, A. Dalgarno

Advances in atomic, molecular, and optical physics•Jan 1, 2005•3 citations

Dipole polarizability of 2S13 and 2S01 metastable helium measured by the electric deflection time-of-flight method

David A. Crosby, Jens C. Zorn

The static dipole polarizability of helium atoms in the metastable $2^{3}S_{1}$ and $2^{1}S_{0}$ states has been determined by measuring the deflection of a beam of excited helium atoms that is caused by an inhomogeneous electric field of known properties. The necessary velocity distribution information is obtained from time-of-flight measurements, and a resonance quenching technique made it possible to distinguish the singlet and triplet components of the beam. The results, $\ensuremath{\alpha}(2^{3}S_{1})=(44.6\ifmmode\pm\else\textpm\fi{}3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{3}$ and $\ensuremath{\alpha}(2^{1}S_{0})=(108\ifmmode\pm\else\textpm\fi{}13)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{3}$, agree with the theoretical value that has been used to calibrate earlier polarizability measurements of the alkali metals and the heavier noble gases.

Physical Review A•Aug 1, 1977•25 citations

Properties of the triplet metastable states of the alkaline-earth-metal atoms

J. Mitroy, M. W. J. Bromley

The static and dynamic properties of the alkaline-earth-metal atoms in their metastable state are computed in a configuration interaction approach with a semiempirical model potential for the core. Among the properties determined are the scalar and tensor polarizabilities, the quadrupole moment, some of the oscillator strengths, and the dispersion coefficients of the van der Waals interaction. A simple method for including the effect of the core on the dispersion parameters is described.

arXiv:physics/0408120•Physical Review A•Nov 11, 2004•33 citations

Moleculelike metastable states of antiprotonic and mesic helium

Isao Shimamura

The exotic helium atom, consisting of a helium nucleus ${\mathrm{He}}^{2+}$, an electron ${\mathit{e}}^{\mathrm{\ensuremath{-}}}$, and a massive, negatively charged particle ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$, such as an antiproton (p\ifmmode\bar\else\textasciimacron\fi{}) or a kaon (${\mathit{K}}^{\mathrm{\ensuremath{-}}}$), is studied theoretically. This exotic atom is more like a polar molecule with two nuclei ${\mathrm{He}}^{2+}$ and ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$, if ${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ is in a low-lying orbital and ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ is in a highly excited orbital. Such states are generally formed in the capture of ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ by helium. The Born-Oppenheimer (BO) separation of the ${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ motion and the ${\mathrm{He}}^{2+}$-${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ motion is a good approximation for these states, and affords a transparent, unified perspective of exotic helium with different ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ and different isotopes of ${\mathrm{He}}^{2+}$. A propensity rule that favors small transition energies (except for the smallest one) is found for radiative emission by low vibrational and high rotational levels. This rule resembles the selection rule for infrared emission by the usual diatomic polar molecules, and contradicts the conventional expectation that radiative transitions in exotic atoms favor larger transition energies. The radiative lifetimes \ensuremath{\tau} of highly excited states formed immediately after the capture of ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ are of the order of \ensuremath{\mu}sec for $^{4}\mathrm{He}^{2+}$-p\ifmmode\bar\else\textasciimacron\fi{}-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ and $^{3}\mathrm{He}^{2+}$-p\ifmmode\bar\else\textasciimacron\fi{}-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$, and those for $^{4}\mathrm{He}^{2+}$-${\mathit{K}}^{\mathrm{\ensuremath{-}}}$-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ are about half the values for the antiprotonic helium.The effect of the electronic charge polarization by ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ on \ensuremath{\tau} is explained quantitatively in a simple picture in terms of the molecular dipole moment. Low vibrational, high rotational states are described as circular or near-circular states in the atomic picture. They are stable against Auger decay, which the nonadiabatic perturbation on the BO states induces. An infinite series of bound \ensuremath{\Sigma} electronic states of exotic helium negative ions (${\mathrm{He}}^{2+}$-${\mathit{X}}^{\mathrm{\ensuremath{-}}}$-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$)-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ exists for any ${\mathrm{He}}^{2+}$-${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ distances R beyond 0.819 a.u. in the BO approximation. An infinite \ensuremath{\Pi} series exists for R>3.811 a.u., and an infinite \ensuremath{\Delta} series for R>9.532 a.u.

Physical Review A•Oct 1, 1992•135 citations

ANALYSIS OF ALKALI METAL ATOMIC POLARIZABILITIES AND DEVELOPING ATOM INTERFEROMETRY WITH METASTABLE HELIUM

Nathan J. Brooks

Atom interferometry is a powerful method for precision measurements of atomic properties such as polarizability, which quantifies the energy shift of an atom due to an applied electric field. In this work, we interpret recent Cs, Rb, K, and Na atomic polarizability measurements in terms of transition matrix elements, excited state lifetimes, and atomic oscillator strengths. We also use these measurements to improve calculations of van der Waals atom-atom interaction potentials. We then combine measurements of polarizability and van der Waals potentials in order to empirically quantify the e↵ect of atomic core (inner-shell) electrons on these properties. This novel method expands the utility of atom interferometry as a test for modern atomic structure calculations. In addition, we explore the possibility of extending our polarizability measurements to metastable helium atoms, for the purpose of reducing systematic errors in our existing measurements, and to strontium atoms, of interest in the construction of next-generation atomic clocks.

•Jan 1, 2016•0 citations

Long-range interactions of metastable helium atoms

Zong-Chao Yan, J. F. Babb

The electric dipole, quadrupole, and octupole polarizabilities of a helium atom and the associated dispersion coefficients for the interaction of two helium atoms are calculated for the atomic $n=2$ singlet and triplet states, respectively, $\mathrm{He}(2{}^{1}S)$ and $\mathrm{He}(2{}^{3}S)$. The calculations utilize highly accurate, variationally determined, wave functions composed of doubled basis sets. The effects of retardation due to the finite speed of light are calculated for the dispersion potentials of two $\mathrm{He}(2{}^{1}S)$ or two $\mathrm{He}(2{}^{3}S)$ atoms and for the atom-surface interaction potentials of a $\mathrm{He}(2{}^{1}S)$ or a $\mathrm{He}(2{}^{3}S)$ atom with a perfectly conducting or a dielectric wall.

arXiv:physics/9802054•Physical Review A•Aug 1, 1998•92 citations
The available theoretical values of the oscillator strengths of dipole transitions from each of the metastable states of helium are modified so that each set satisfies four different sum rules. They are then employed to evaluate the polarizabilities, the diamagnetic susceptibilities, the average energy losses for fast particle impact, the Lamb shift average excitation energies and the van der Waals interactions between normal and metastable helium atoms.
The static dipole polarizability of helium atoms in the metastable 23S12^{3}S_{1}23S1​ and 21S02^{1}S_{0}21S0​ states has been determined by measuring the deflection of a beam of excited helium atoms that is caused by an inhomogeneous electric field of known properties. The necessary velocity distribution information is obtained from time-of-flight measurements, and a resonance quenching technique made it possible to distinguish the singlet and triplet components of the beam. The results, $\ensuremath{\alpha}(2^{3}S_{1})=(44.6\ifmmode\pm\else\textpm\fi{}3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}$ cm3{\mathrm{cm}}^{3}cm3 and $\ensuremath{\alpha}(2^{1}S_{0})=(108\ifmmode\pm\else\textpm\fi{}13)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}$ cm3{\mathrm{cm}}^{3}cm3, agree with the theoretical value that has been used to calibrate earlier polarizability measurements of the alkali metals and the heavier noble gases.
The exotic helium atom, consisting of a helium nucleus He2+{\mathrm{He}}^{2+}He2+, an electron ${\mathit{e}}^{\mathrm{\ensuremath{-}}}$, and a massive, negatively charged particle ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$, such as an antiproton (p\ifmmode\bar\else\textasciimacron\fi{}) or a kaon (${\mathit{K}}^{\mathrm{\ensuremath{-}}}$), is studied theoretically. This exotic atom is more like a polar molecule with two nuclei He2+{\mathrm{He}}^{2+}He2+ and ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$, if ${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ is in a low-lying orbital and ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ is in a highly excited orbital. Such states are generally formed in the capture of ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ by helium. The Born-Oppenheimer (BO) separation of the ${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ motion and the He2+{\mathrm{He}}^{2+}He2+-${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ motion is a good approximation for these states, and affords a transparent, unified perspective of exotic helium with different ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ and different isotopes of He2+{\mathrm{He}}^{2+}He2+. A propensity rule that favors small transition energies (except for the smallest one) is found for radiative emission by low vibrational and high rotational levels. This rule resembles the selection rule for infrared emission by the usual diatomic polar molecules, and contradicts the conventional expectation that radiative transitions in exotic atoms favor larger transition energies. The radiative lifetimes \ensuremath{\tau} of highly excited states formed immediately after the capture of ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ are of the order of \ensuremath{\mu}sec for 4He2+^{4}\mathrm{He}^{2+}4He2+-p\ifmmode\bar\else\textasciimacron\fi{}-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ and 3He2+^{3}\mathrm{He}^{2+}3He2+-p\ifmmode\bar\else\textasciimacron\fi{}-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$, and those for 4He2+^{4}\mathrm{He}^{2+}4He2+-${\mathit{K}}^{\mathrm{\ensuremath{-}}}$-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ are about half the values for the antiprotonic helium.The effect of the electronic charge polarization by ${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ on \ensuremath{\tau} is explained quantitatively in a simple picture in terms of the molecular dipole moment. Low vibrational, high rotational states are described as circular or near-circular states in the atomic picture. They are stable against Auger decay, which the nonadiabatic perturbation on the BO states induces. An infinite series of bound \ensuremath{\Sigma} electronic states of exotic helium negative ions (He2+{\mathrm{He}}^{2+}He2+-${\mathit{X}}^{\mathrm{\ensuremath{-}}}$-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$)-${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ exists for any He2+{\mathrm{He}}^{2+}He2+-${\mathit{X}}^{\mathrm{\ensuremath{-}}}$ distances R beyond 0.819 a.u. in the BO approximation. An infinite \ensuremath{\Pi} series exists for R>3.811 a.u., and an infinite \ensuremath{\Delta} series for R>9.532 a.u.
Atom interferometry is a powerful method for precision measurements of atomic properties such as polarizability, which quantifies the energy shift of an atom due to an applied electric field. In this work, we interpret recent Cs, Rb, K, and Na atomic polarizability measurements in terms of transition matrix elements, excited state lifetimes, and atomic oscillator strengths. We also use these measurements to improve calculations of van der Waals atom-atom interaction potentials. We then combine measurements of polarizability and van der Waals potentials in order to empirically quantify the e↵ect of atomic core (inner-shell) electrons on these properties. This novel method expands the utility of atom interferometry as a test for modern atomic structure calculations. In addition, we explore the possibility of extending our polarizability measurements to metastable helium atoms, for the purpose of reducing systematic errors in our existing measurements, and to strontium atoms, of interest in the construction of next-generation atomic clocks.
The electric dipole, quadrupole, and octupole polarizabilities of a helium atom and the associated dispersion coefficients for the interaction of two helium atoms are calculated for the atomic n=2n=2n=2 singlet and triplet states, respectively, He(21S)\mathrm{He}(2{}^{1}S)He(21S) and He(23S)\mathrm{He}(2{}^{3}S)He(23S). The calculations utilize highly accurate, variationally determined, wave functions composed of doubled basis sets. The effects of retardation due to the finite speed of light are calculated for the dispersion potentials of two He(21S)\mathrm{He}(2{}^{1}S)He(21S) or two He(23S)\mathrm{He}(2{}^{3}S)He(23S) atoms and for the atom-surface interaction potentials of a He(21S)\mathrm{He}(2{}^{1}S)He(21S) or a He(23S)\mathrm{He}(2{}^{3}S)He(23S) atom with a perfectly conducting or a dielectric wall.