Canadian Journal of Physics

Hanle effect in the singlet excited states of the alkaline earths

F. M. Kelly, M. S. Mathur

Published Oct 1, 1980• 42 citations

Abstract

The Hanle effect in the singlet states of Sr, Ba, Mg, and Ca has been studied over a range of densities. The low density observations lead to an accurate lifetime measurement of the singlet excited levels, and calculation of the related oscillator strengths. The depolarization cross sections, [Formula: see text], for collision with ground level neutral atoms have been obtained from the high density data.

DOI: 10.1139/p80-181

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Canadian Journal of Physics

Hanle effect in the singlet excited states of the alkaline earths

F. M. Kelly, M. S. Mathur

Published Oct 1, 1980• 42 citations

Publisher

Abstract

DOI: 10.1139/p80-181

Related papers

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

F. M. Kelly, M. S. Mathur

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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F. M. Kelly, M. S. Mathur

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Oscillator Strengths of Ca II, Sr II, and Ba II

Alan C. Gallagher

The lifetimes of the $5p^{2}P_{\frac{3}{2}}$ and $5p^{2}P_{\frac{1}{2}}$ states of ${\mathrm{Sr}}^{+}$ and the $6p^{2}P_{\frac{3}{2}}$ and $6p^{2}P_{\frac{1}{2}}$ states of ${\mathrm{Ba}}^{+}$ have been measured by the Hanle-effect technique with optical excitation from the ion ground state. (The lifetimes of the ${\mathrm{Mg}}^{+}$ $3p^{2}P_{\frac{3}{2}}$ and ${\mathrm{Ca}}^{+}$ $4p^{2}P_{\frac{3}{2}}$ states were obtained by the same technique and reported previously.) These ${\mathrm{Ca}}^{+}$ , ${\mathrm{Sr}}^{+}$ , and ${\mathrm{Ba}}^{+}$ states each decay to a $^{2}D_{\frac{3}{2},\frac{5}{2}}$ doublet as well as to the ground $^{2}S_{\frac{1}{2}}$ state, and the branching ratios for these transitions have been measured. The ions were produced by introducing traces of the atomic vapor into an argon discharge. Consequently, the cross sections for collisional depolarization of these $^{2}P_{J}$ states due to collisions with argon were also obtained from the measurements. The experimental results are given in Tables I and II. A discussion of the ion-atom collisional depolarization cross sections is included.The lifetimes of the $5p^{2}P_{\frac{3}{2}}$ and $5p^{2}P_{\frac{1}{2}}$ states of ${\mathrm{Sr}}^{+}$ and the $6p^{2}P_{\frac{3}{2}}$ and $6p^{2}P_{\frac{1}{2}}$ states of ${\mathrm{Ba}}^{+}$ have been measured by the Hanle-effect technique with optical excitation from the ion ground state. (The lifetimes of the ${\mathrm{Mg}}^{+}$ $3p^{2}P_{\frac{3}{2}}$ and ${\mathrm{Ca}}^{+}$ $4p^{2}P_{\frac{3}{2}}$ states were obtained by the same technique and reported previously.) These ${\mathrm{Ca}}^{+}$, ${\mathrm{Sr}}^{+}$, and ${\mathrm{Ba}}^{+}$ states each decay to a $^{2}D_{\frac{3}{2},\frac{5}{2}}$ doublet as well as to the ground $^{2}S_{\frac{1}{2}}$ state, and the branching ratios for these transitions have been measured. The ions were produced by introducing traces of the atomic vapor into an argon discharge. Consequently, the cross sections for collisional depolarization of these $^{2}P_{J}$ states due to collisions with argon were also obtained from the measurements. The experimental results are given in Tables I and II. A discussion of the ion-atom collisional depolarization cross sections is included.

Physical ReviewMay 5, 1967217 citations

The Hanle effect in Penning-excited ions

David W. Fahey, W. F. Parks, L. D. Schearer

A thermal beam of helium (2 3 S 1 ) metastable atoms was used to excite coherently the 2 P 3/2 levels of Ca, Sr and Ba in a Penning ionising collision. The coherent excitation of the ions appears as a linear polarisation of the optical emission from the excited ions. The degree of linear polarisation is 5.5, 3.5 and 0.5% for Ca, Sr and Ba, respectively, with the polarisation parallel to the beam direction. Hanle effect signals from the 2 P 3/2 level of Sr were observed and the radioactive decay rate measured.A thermal beam of helium (2 3 S 1 ) metastable atoms was used to excite coherently the 2 P 3/2 levels of Ca, Sr and Ba in a Penning ionising collision. The coherent excitation of the ions appears as a linear polarisation of the optical emission from the excited ions. The degree of linear polarisation is 5.5, 3.5 and 0.5% for Ca, Sr and Ba, respectively, with the polarisation parallel to the beam direction. Hanle effect signals from the 2 P 3/2 level of Sr were observed and the radioactive decay rate measured.

Journal of Physics B Atomic and Molecular PhysicsOct 28, 19795 citations

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 lifetimes of the

5p^{2}P_{\frac{3}{2}}

and

5p^{2}P_{\frac{1}{2}}

states of

{\mathrm{Sr}}^{+}

and the

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

and

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

states of

{\mathrm{Ba}}^{+}

have been measured by the Hanle-effect technique with optical excitation from the ion ground state. (The lifetimes of the

{\mathrm{Mg}}^{+}

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

and

{\mathrm{Ca}}^{+}

4p^{2}P_{\frac{3}{2}}

states were obtained by the same technique and reported previously.) These

{\mathrm{Ca}}^{+}

{\mathrm{Sr}}^{+}

, and

{\mathrm{Ba}}^{+}

states each decay to a

^{2}D_{\frac{3}{2},\frac{5}{2}}

doublet as well as to the ground

^{2}S_{\frac{1}{2}}

state, and the branching ratios for these transitions have been measured. The ions were produced by introducing traces of the atomic vapor into an argon discharge. Consequently, the cross sections for collisional depolarization of these

^{2}P_{J}

states due to collisions with argon were also obtained from the measurements. The experimental results are given in Tables I and II. A discussion of the ion-atom collisional depolarization cross sections is included.