Quantum Electronics

Probability of the 21S0— 23S1forbidden transition in the helium atom

E. V. Baklanov, A V Denisov

Published May 31, 1997• 3 citations

Abstract

The probability W of the forbidden magnetic-dipole 2 1 S 0 — 2 3 S 1 transition in the helium atom is calculated to be 6.11 × 10 -8 s -1 . An estimate is obtained of the number of atoms excited to the 2 1 S 0 state by a travelling wave which is in resonance with the frequency of this transition.

DOI: 10.1070/qe1997v027n05abeh000963

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Quantum Electronics

Probability of the 21S0— 23S1forbidden transition in the helium atom

E. V. Baklanov, A V Denisov

Published May 31, 1997• 3 citations

Publisher

Abstract

DOI: 10.1070/qe1997v027n05abeh000963

Related papers

Precision measurement of the forbidden 21S0 – 23S1 transition frequency in a helium atom

E. V. Baklanov, P.V. Pokasov, А. В. Тайченачев

Quantum ElectronicsMay 7, 20181 citation

On the measurement of forbidden 21S0 – 23S1 transition frequency in helium by the method of stimulated Raman scattering

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AIP conference proceedingsJan 1, 20190 citations

Resonant Stimulated Raman Scattering from the 23S–11S Forbidden Transition in a Helium Atom

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The interaction of normal and metastable helium atoms

Richard A. Buckingham, A. Dalgarno

Abstract The energy of interaction of a normal helium atom and one excited to the first triplet or singlet metastable state is calculated over a range of nuclear separations from a0 to 12a0. The Heitler-London method is followed, with inclusion of all non-orthogonality integrals, and using analytic wave functions. Because of identity of the nuclei, g and u states of interaction occur, the energy of the u state having a minimum at about 2·1a0, and a positive maximum of 0·29 and 0·26 eV (for triplet and singlet states respectively) at about 4a0; the g state is entirely repulsive. Comparison is made with experimental evidence for the binding energy of normal and metastable (triplet) atoms. An estimate is made of the second-order dipole-dipole interaction for large separations, and it seems certain that the first-order interaction dominates at least to 12a0. Methods of calculating the necessary integrals are discussed in an appendix.Abstract The energy of interaction of a normal helium atom and one excited to the first triplet or singlet metastable state is calculated over a range of nuclear separations from a0 to 12a0. The Heitler-London method is followed, with inclusion of all non-orthogonality integrals, and using analytic wave functions. Because of identity of the nuclei, g and u states of interaction occur, the energy of the u state having a minimum at about 2·1a0, and a positive maximum of 0·29 and 0·26 eV (for triplet and singlet states respectively) at about 4a0; the g state is entirely repulsive. Comparison is made with experimental evidence for the binding energy of normal and metastable (triplet) atoms. An estimate is made of the second-order dipole-dipole interaction for large separations, and it seems certain that the first-order interaction dominates at least to 12a0. Methods of calculating the necessary integrals are discussed in an appendix.

Proceedings of the Royal Society of London A Mathematical and Physical SciencesJul 8, 195287 citations

Resonant stimulated Raman scattering (SRS) from the

{{2}^{3}}S{-} {{1}^{1}}S

forbidden transition in a helium atom (62.6 nm) via the intermediate

{{2}^{3}}{{P}_{1}}

level has been considered. The metastable

{{2}^{3}}S

state has the lowest energy in the triplet spectral region (He*), and the ground state is

{{1}^{1}}S

. The reduced kinetic equations for the density matrix, which are used to analyze the SRS resonance, have been derived. The expressions for the field broadening and resonance shift are obtained, the Doppler broadening is taken into account, and numerical estimations are performed.

We have measured the forbidden $2\text{ }^{3}{S}_{1}\ensuremath{\rightarrow}2\text{ }^{1}{P}_{1}$ transition at 887 nm in a quantum degenerate gas of metastable

^{4}\mathrm{He}

atoms confined in an optical dipole trap. The determined transition frequency is 338 133 594.4 (0.5) MHz, from which we obtain an ionization energy of the

2\text{ }^{1}{P}_{1}

state of 814 709 148.6 (0.5) MHz. This ionization energy is in disagreement by $>3\ensuremath{\sigma}$ with the most accurate quantum electrodynamics calculations available. Our measurements also provide a new determination of the lifetime of the

2\text{ }^{1}{P}_{1}

state of $0.551\text{ }(0.004{)}_{\text{stat}}\text{ }{(}_{\ensuremath{-}0.000}^{+0.013}{)}_{\text{syst}}\text{ }\text{ }\mathrm{ns}$, which is the most accurate determination to date and in excellent agreement with theory.