Canadian Journal of Physics

Lifetime of the 6s6p1P1 level of barium

L. O. Dickie, F. M. Kelly

Published Apr 1, 1970• 19 citations

Abstract

The lifetime of the first excited singlet P level of barium, 6s6p1P1, has been determined from the width of the zero field level crossing, i.e. the Hanle effect, of the 6s6p1P1 –6s21S0, 5535 Å resonance line. The resonance radiation was produced in a hollow cathode lamp and the scattering atoms by an atomic beam. After taking account of coherence narrowing, the lifetime is determined to be 8.37 ± 0.14 × 10−9 s, in good agreement with other recent work.

DOI: 10.1139/p70-114

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Canadian Journal of Physics

Lifetime of the 6s6p1P1 level of barium

L. O. Dickie, F. M. Kelly

Published Apr 1, 1970• 19 citations

Publisher

Abstract

DOI: 10.1139/p70-114

Related papers

The density dependence of the Hanle effect in the resonance line of atomic barium

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The change in the Hanle effect of the singlet resonance line of neutral barium has been studied over a wide range of density. The low density region has been used to confirm a lifetime of 8.37 ± 0.08 ns for the 6s6p1P1 level. We have determined the cross sections for the relaxation of the multipole moment of order 2 for collisions of the excited level with the ground level and with the metastable 6s5d1D2 level, and comparisons are made with the measured value of [Formula: see text] for the ground level with theoretical predictions.The change in the Hanle effect of the singlet resonance line of neutral barium has been studied over a wide range of density. The low density region has been used to confirm a lifetime of 8.37 ± 0.08 ns for the 6s6p1P1 level. We have determined the cross sections for the relaxation of the multipole moment of order 2 for collisions of the excited level with the ground level and with the metastable 6s5d1D2 level, and comparisons are made with the measured value of [Formula: see text] for the ground level with theoretical predictions.

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Hanle Effect in 2P1 Helium

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The oscillator strength for the resonance ($1^{1}S\ensuremath{-}2^{1}P$) transition in atomic helium has been determined from a measurement of the lifetime of the $2^{1}P$ state. This lifetime was obtained using a modified zero-field level crossing (Hanle) method. The scattering sample was a thermal velocity beam of $2^{1}S$ metastable atoms. Resonant 2-\ensuremath{\mu} ($2^{1}S\ensuremath{-}2^{1}P$) radiation is absorbed by the $2^{1}S$ atoms, which are excited to the $2^{1}P$ state. This state then primarily decays to the ground $1^{1}S$ state with the emission of resonance (584 \AA{}) radiation. The lifetime of the $2^{1}P$ state was determined from measurements of the magnetic-field dependence of the angular distribution of the 584 \AA{} intensity. This new technique eliminates the problem of constructing a vacuum ultraviolet resonance lamp. The measured lifetime $\ensuremath{\tau} (2^{1}P)$ is (5.63 \ifmmode\pm\else\textpm\fi{} 0.22) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}10}$ sec. The resulting absorption oscillator strength for the resonance transition is 0.273 \ifmmode\pm\else\textpm\fi{} 0.011. This oscillator strength agrees with the theoretical value.The oscillator strength for the resonance ($1^{1}S\ensuremath{-}2^{1}P$) transition in atomic helium has been determined from a measurement of the lifetime of the $2^{1}P$ state. This lifetime was obtained using a modified zero-field level crossing (Hanle) method. The scattering sample was a thermal velocity beam of $2^{1}S$ metastable atoms. Resonant 2-\ensuremath{\mu} ($2^{1}S\ensuremath{-}2^{1}P$) radiation is absorbed by the $2^{1}S$ atoms, which are excited to the $2^{1}P$ state. This state then primarily decays to the ground $1^{1}S$ state with the emission of resonance (584 \AA{}) radiation. The lifetime of the $2^{1}P$ state was determined from measurements of the magnetic-field dependence of the angular distribution of the 584 \AA{} intensity. This new technique eliminates the problem of constructing a vacuum ultraviolet resonance lamp. The measured lifetime $\ensuremath{\tau} (2^{1}P)$ is (5.63 \ifmmode\pm\else\textpm\fi{} 0.22) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}10}$ sec. The resulting absorption oscillator strength for the resonance transition is 0.273 \ifmmode\pm\else\textpm\fi{} 0.011. This oscillator strength agrees with the theoretical value.

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Jan 1, 19690 citations

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6pP2 levels of ionized barium: Lifetimes and depolarization cross sections

F. M. Kelly, M. S. Mathur

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James M. Burger, Allen Lurio

The radiative lifetime of the $2^{1}P_{1}$ and $3^{1}P_{1}$ state of atomic helium has been measured by the level-crossing technique. In the experiment, a beam of $2^{1}S_{0}$ metastable atoms was first produced and then excited to the $2^{1}P_{1}$ or $3^{1}P_{1}$ state with resonance radiation. The lifetimes were measured by observing the zero-field level-crossing signals in the detected 584- or 537-\AA{} fluorescent radiation when these $^{1}P_{1}$ states decayed to the $1^{1}S_{0}$ ground state. The results are $\ensuremath{\tau} (2^{1}P_{1})=(5.57\ifmmode\pm\else\textpm\fi{}0.15)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ sec and $\ensuremath{\tau} (3^{1}P_{1})=(1.73\ifmmode\pm\else\textpm\fi{}0.11)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ sec. These values are in excellent agreement with theory.The radiative lifetime of the $2^{1}P_{1}$ and $3^{1}P_{1}$ state of atomic helium has been measured by the level-crossing technique. In the experiment, a beam of $2^{1}S_{0}$ metastable atoms was first produced and then excited to the $2^{1}P_{1}$ or $3^{1}P_{1}$ state with resonance radiation. The lifetimes were measured by observing the zero-field level-crossing signals in the detected 584- or 537-\AA{} fluorescent radiation when these $^{1}P_{1}$ states decayed to the $1^{1}S_{0}$ ground state. The results are $\ensuremath{\tau} (2^{1}P_{1})=(5.57\ifmmode\pm\else\textpm\fi{}0.15)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ sec and $\ensuremath{\tau} (3^{1}P_{1})=(1.73\ifmmode\pm\else\textpm\fi{}0.11)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ sec. These values are in excellent agreement with theory.

Physical Review AJan 1, 197121 citations

The oscillator strength for the resonance ($1^{1}S\ensuremath{-}2^{1}P$) transition in atomic helium has been determined from a measurement of the lifetime of the

2^{1}P

state. This lifetime was obtained using a modified zero-field level crossing (Hanle) method. The scattering sample was a thermal velocity beam of

2^{1}S

metastable atoms. Resonant 2-\ensuremath{\mu} ($2^{1}S\ensuremath{-}2^{1}P$) radiation is absorbed by the

2^{1}S

atoms, which are excited to the

2^{1}P

state. This state then primarily decays to the ground

1^{1}S

state with the emission of resonance (584 \AA{}) radiation. The lifetime of the

2^{1}P

state was determined from measurements of the magnetic-field dependence of the angular distribution of the 584 \AA{} intensity. This new technique eliminates the problem of constructing a vacuum ultraviolet resonance lamp. The measured lifetime $\ensuremath{\tau} (2^{1}P)$ is (5.63 \ifmmode\pm\else\textpm\fi{} 0.22) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}10}$ sec. The resulting absorption oscillator strength for the resonance transition is 0.273 \ifmmode\pm\else\textpm\fi{} 0.011. This oscillator strength agrees with the theoretical value.

The Hanle effect and its variation with density has been used to determine the depolarization cross section for collisions between the

^{2}P_{\frac{3}{2}}

barium ions and neutral atoms. An extrapolation of the data to zero density gives a value of the average lifetime $\ensuremath{\tau}=6.22$ ns for the

6p^{2}P_{\frac{3}{2}}

level. A further experiment gives $\ensuremath{\tau}=7.55$ ns for the

6p^{2}P_{\frac{1}{2}}

level.

The radiative lifetime of the

2^{1}P_{1}

and

3^{1}P_{1}

state of atomic helium has been measured by the level-crossing technique. In the experiment, a beam of

2^{1}S_{0}

metastable atoms was first produced and then excited to the

2^{1}P_{1}

3^{1}P_{1}

state with resonance radiation. The lifetimes were measured by observing the zero-field level-crossing signals in the detected 584- or 537-\AA{} fluorescent radiation when these

^{1}P_{1}

states decayed to the

1^{1}S_{0}

ground state. The results are $\ensuremath{\tau} (2^{1}P_{1})=(5.57\ifmmode\pm\else\textpm\fi{}0.15)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ sec and $\ensuremath{\tau} (3^{1}P_{1})=(1.73\ifmmode\pm\else\textpm\fi{}0.11)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ sec. These values are in excellent agreement with theory.