Physical Review

Energy Shifts of the Magnetic Sublevels of S13 Helium Caused by Optical Pumping

L. D. Schearer

Published Jul 15, 1962• 26 citations

Abstract

It has been observed experimentally that the energy spacing between the magnetic sublevels of the $2^{3}S_{1}$ state of helium as detected by optical pumping varies with the intensity and character of the resonant radiation. The relative shift as a function of the intensity, polarization, and spectral distribution are observed and measured. The energy shifts are on the order of 50-60 cps and become smaller as the intensity of the light decreases. A second lamp containing ${\mathrm{He}}^{3}$ incident on the absorption cell in the same manner as the pumping lamp also produces an energy shift. An explanation of the light shift in metastable helium is discussed.

DOI: 10.1103/physrev.127.512

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Optical Pumping of Helium in the S13 Metastable State

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Physical Review

Energy Shifts of the Magnetic Sublevels of S13 Helium Caused by Optical Pumping

L. D. Schearer

Published Jul 15, 1962• 26 citations

Publisher

Abstract

It has been observed experimentally that the energy spacing between the magnetic sublevels of the

2^{3}S_{1}

state of helium as detected by optical pumping varies with the intensity and character of the resonant radiation. The relative shift as a function of the intensity, polarization, and spectral distribution are observed and measured. The energy shifts are on the order of 50-60 cps and become smaller as the intensity of the light decreases. A second lamp containing

{\mathrm{He}}^{3}

incident on the absorption cell in the same manner as the pumping lamp also produces an energy shift. An explanation of the light shift in metastable helium is discussed.

DOI: 10.1103/physrev.127.512

Related papers

Optical Pumping of Helium in the S13 Metastable State

F. D. Colegrove, P. A. Franken

The alignment of ${\mathrm{He}}^{4}$ atoms in the ( $n=2$ , metastable) $^{3}S_{1}$ state is described. Metastable atoms are produced by an rf discharge in a glass tube containing a few mm of pure helium, and the one micron pumping light ($2^{3}P\ensuremath{-}2^{3}S$) is provided by a helium lamp. A resonance signal is obtained from radio frequency disorientation by monitoring the transmitted pumping light. The double maximum line shape of this signal for strong rf magnetic fields is discussed. Included also is a discussion of the angular dependence of the signal when unpolarized light is used and an explanation of the inversion of the resonance signal for certain densities of the metastable helium atoms.The measured relaxation time of the oriented metastable atoms in the discharge is about 2.5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ second and the pumping time is about a millisecond. A method is proposed and initial measurements are given for the cross section for destruction of metastable helium atoms by collision with foreign gas atoms. The application of optical pumping in helium to the measurement of weak magnetic fields is also discussed.The alignment of ${\mathrm{He}}^{4}$ atoms in the ($n=2$, metastable) $^{3}S_{1}$ state is described. Metastable atoms are produced by an rf discharge in a glass tube containing a few mm of pure helium, and the one micron pumping light ($2^{3}P\ensuremath{-}2^{3}S$) is provided by a helium lamp. A resonance signal is obtained from radio frequency disorientation by monitoring the transmitted pumping light. The double maximum line shape of this signal for strong rf magnetic fields is discussed. Included also is a discussion of the angular dependence of the signal when unpolarized light is used and an explanation of the inversion of the resonance signal for certain densities of the metastable helium atoms.The measured relaxation time of the oriented metastable atoms in the discharge is about 2.5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ second and the pumping time is about a millisecond. A method is proposed and initial measurements are given for the cross section for destruction of metastable helium atoms by collision with foreign gas atoms. The application of optical pumping in helium to the measurement of weak magnetic fields is also discussed.

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Stark Shifts Within the (1s2s)S13 State of He

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Physical Review LettersDec 29, 19697 citations

Depolarization of Light Scattered by Aligned 2S3 and 2P3 Helium Atoms at Resonance

L. D. Schearer

The $2^{3}S_{1}$ (metastable) and $2^{3}P_{1,2}$ excited-state atoms of ${\mathrm{He}}^{4}$ are aligned by an unpolarized beam of resonance radiation. The alignment is detected by the depolarization of the resonance fluorescence at 1\ensuremath{\mu}, which occurs when either the $2^{3}S_{1}$ level or the $2^{2}P_{1,2}$ levels are saturated by a rf magnetic field at the Zeeman frequency. The observed signals are several orders of magnitude larger than the corresponding signals observed by monitoring intensity changes in the transmitted beam. Considerably smaller signals are observed even in the absence of the pumping beam. Expressions for the intensity of the $\ensuremath{\pi}$ and $\ensuremath{\sigma}$ components of the scattered radiation are derived in terms of the alignment and density of the metastable atoms. The alignment of the $2^{3}S_{1} (F=\frac{3}{2})$ and the $2^{3}P_{2} (F=\frac{5}{2})$ levels of ${\mathrm{He}}^{3}$ is also observed. The excited-state linewidth as a function of pressure leads to a radiative decay time of $\ensuremath{\tau}\ensuremath{\approx}0.96\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ sec and a mixing cross section of 53\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$ . The alignment of the $3^{3}P$ level of ${\mathrm{He}}^{4}$ is also observed by monitoring polarization changes of the 3889 \AA{} line.The $2^{3}S_{1}$ (metastable) and $2^{3}P_{1,2}$ excited-state atoms of ${\mathrm{He}}^{4}$ are aligned by an unpolarized beam of resonance radiation. The alignment is detected by the depolarization of the resonance fluorescence at 1\ensuremath{\mu}, which occurs when either the $2^{3}S_{1}$ level or the $2^{2}P_{1,2}$ levels are saturated by a rf magnetic field at the Zeeman frequency. The observed signals are several orders of magnitude larger than the corresponding signals observed by monitoring intensity changes in the transmitted beam. Considerably smaller signals are observed even in the absence of the pumping beam. Expressions for the intensity of the $\ensuremath{\pi}$ and $\ensuremath{\sigma}$ components of the scattered radiation are derived in terms of the alignment and density of the metastable atoms. The alignment of the $2^{3}S_{1} (F=\frac{3}{2})$ and the $2^{3}P_{2} (F=\frac{5}{2})$ levels of ${\mathrm{He}}^{3}$ is also observed. The excited-state linewidth as a function of pressure leads to a radiative decay time of $\ensuremath{\tau}\ensuremath{\approx}0.96\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ sec and a mixing cross section of 53\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$. The alignment of the $3^{3}P$ level of ${\mathrm{He}}^{4}$ is also observed by monitoring polarization changes of the 3889 \AA{} line.

Physical ReviewFeb 5, 19688 citations

Observation of the spin polarization of Cs atoms during collisions with oriented metastable helium atoms

Victor A. Kartoshkin, Sergei Dmitriev, N. A. Dovator +1 more

Journal of Physics Conference SeriesSep 7, 20150 citations

Theory of double refraction in a gas due to spin alignment: Observations of birefringence in optically pumped helium

S Pancharatnam

Transverse birefringence has been observed in an aligned spin assembly consisting of helium 4 atoms in the metastable state 2 3 S 1 . The alignment of the spins was produced by optical pumping with unpolarized light. Using a cross-beam of off-resonant radiation, for example from a helium 3 lamp, together with a suitable combination of polarizer and analyser, birefringence signals could be displayed analogous to the absorption signals conventionally used for the optical monitoring of magnetic resonance. An analysis of the phenomenon is given, showing quite generally that birefringence monitors separately the degree of alignment of the spin assembly, even when orientation is also present; the latter can be monitored by the magnetic rotation of the plane of polarization for axial light. The analysis also includes the effect of the spectral characteristics of the monitoring lamp, i.e. the central frequencies of emission and the Doppler width, on the strengths of absorption and birefringence signals displayed by optically thin samples.Transverse birefringence has been observed in an aligned spin assembly consisting of helium 4 atoms in the metastable state 2 3 S 1 . The alignment of the spins was produced by optical pumping with unpolarized light. Using a cross-beam of off-resonant radiation, for example from a helium 3 lamp, together with a suitable combination of polarizer and analyser, birefringence signals could be displayed analogous to the absorption signals conventionally used for the optical monitoring of magnetic resonance. An analysis of the phenomenon is given, showing quite generally that birefringence monitors separately the degree of alignment of the spin assembly, even when orientation is also present; the latter can be monitored by the magnetic rotation of the plane of polarization for axial light. The analysis also includes the effect of the spectral characteristics of the monitoring lamp, i.e. the central frequencies of emission and the Doppler width, on the strengths of absorption and birefringence signals displayed by optically thin samples.

Journal of Physics B Atomic and Molecular PhysicsMar 1, 19684 citations

Experimental Study of Zeeman Light Shifts in Weak Magnetic Fields

Claude N. Cohen-Tannoudji, J. Dupont-Roc

According to the quantum theory of the optical-pumping cycle, one can describe the effect of a nonresonant light beam on the different Zeeman sublevels of an atomic ground state by an effective Hamiltonian ${\mathcal{H}}_{e}$ which depends on the polarization and spectral profile of the incident light. In order to check the structure of ${\mathcal{H}}_{e}$ , we have performed a detailed experimental study of the ground-state energy sublevels of various kinds of atoms perturbed by different types of nonresonant light beams. Attention is paid to the modification of the Zeeman structure due to ${\mathcal{H}}_{e}$ . We have been able to obtain experimentally in the ground state of $^{199}\mathrm{Hg}$ , $^{201}\mathrm{Hg}$ , and $^{87}\mathrm{Rb}$ , Zeeman light shifts that are larger than the width of the levels due to the thermal relaxation. The removal of the Zeeman degeneracy in zero external field, due to a nonresonant light irradiation, is observed by different optical-pumping techniques; the full Zeeman diagram of the perturbed atoms is also determined when a static field ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}}_{0}$ is added. We have checked that the effect of ${\mathcal{H}}_{e}$ can be described in terms of fictitious static electric or magnetic fields. These fictitious fields can be used to act selectively on a given atomic level.According to the quantum theory of the optical-pumping cycle, one can describe the effect of a nonresonant light beam on the different Zeeman sublevels of an atomic ground state by an effective Hamiltonian ${\mathcal{H}}_{e}$ which depends on the polarization and spectral profile of the incident light. In order to check the structure of ${\mathcal{H}}_{e}$, we have performed a detailed experimental study of the ground-state energy sublevels of various kinds of atoms perturbed by different types of nonresonant light beams. Attention is paid to the modification of the Zeeman structure due to ${\mathcal{H}}_{e}$. We have been able to obtain experimentally in the ground state of $^{199}\mathrm{Hg}$, $^{201}\mathrm{Hg}$, and $^{87}\mathrm{Rb}$, Zeeman light shifts that are larger than the width of the levels due to the thermal relaxation. The removal of the Zeeman degeneracy in zero external field, due to a nonresonant light irradiation, is observed by different optical-pumping techniques; the full Zeeman diagram of the perturbed atoms is also determined when a static field ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}}_{0}$ is added. We have checked that the effect of ${\mathcal{H}}_{e}$ can be described in terms of fictitious static electric or magnetic fields. These fictitious fields can be used to act selectively on a given atomic level.

Physical Review AFeb 1, 1972265 citations

It has been observed experimentally that the energy spacing between the magnetic sublevels of the

2^{3}S_{1}

{\mathrm{He}}^{3}

incident on the absorption cell in the same manner as the pumping lamp also produces an energy shift. An explanation of the light shift in metastable helium is discussed.

The alignment of

{\mathrm{He}}^{4}

atoms in the (

n=2

, metastable)

^{3}S_{1}

state is described. Metastable atoms are produced by an rf discharge in a glass tube containing a few mm of pure helium, and the one micron pumping light ($2^{3}P\ensuremath{-}2^{3}S$) is provided by a helium lamp. A resonance signal is obtained from radio frequency disorientation by monitoring the transmitted pumping light. The double maximum line shape of this signal for strong rf magnetic fields is discussed. Included also is a discussion of the angular dependence of the signal when unpolarized light is used and an explanation of the inversion of the resonance signal for certain densities of the metastable helium atoms.The measured relaxation time of the oriented metastable atoms in the discharge is about 2.5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ second and the pumping time is about a millisecond. A method is proposed and initial measurements are given for the cross section for destruction of metastable helium atoms by collision with foreign gas atoms. The application of optical pumping in helium to the measurement of weak magnetic fields is also discussed.

We have measured the relative Stark shift between the ${m}_{J}=\ifmmode\pm\else\textpm\fi{}1$ and the

{m}_{J}=0

Zeeman sublevels of the

2^{3}S_{1}

metastable state in helium. This shift should be zero in the $L\ensuremath{-}S$ coupling limit. The shifts is (1.27 \ifmmode\pm\else\textpm\fi{}.04) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}6}$ Hz/

{(\mathrm{V}/\mathrm{c}\mathrm{m})}^{2}

, and decreases the normal magnetic field splitting between the

{m}_{J}=+1

and the

{m}_{J}=0

sublevels.

The

2^{3}S_{1}

(metastable) and

2^{3}P_{1,2}

excited-state atoms of

{\mathrm{He}}^{4}

are aligned by an unpolarized beam of resonance radiation. The alignment is detected by the depolarization of the resonance fluorescence at 1\ensuremath{\mu}, which occurs when either the

2^{3}S_{1}

level or the

2^{2}P_{1,2}

levels are saturated by a rf magnetic field at the Zeeman frequency. The observed signals are several orders of magnitude larger than the corresponding signals observed by monitoring intensity changes in the transmitted beam. Considerably smaller signals are observed even in the absence of the pumping beam. Expressions for the intensity of the $\ensuremath{\pi}$ and $\ensuremath{\sigma}$ components of the scattered radiation are derived in terms of the alignment and density of the metastable atoms. The alignment of the

2^{3}S_{1} (F=\frac{3}{2})

and the

2^{3}P_{2} (F=\frac{5}{2})

levels of

{\mathrm{He}}^{3}

is also observed. The excited-state linewidth as a function of pressure leads to a radiative decay time of $\ensuremath{\tau}\ensuremath{\approx}0.96\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ sec and a mixing cross section of 53\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}16}$

{\mathrm{cm}}^{2}

. The alignment of the

3^{3}P

level of

{\mathrm{He}}^{4}

is also observed by monitoring polarization changes of the 3889 \AA{} line.

{\mathcal{H}}_{e}

which depends on the polarization and spectral profile of the incident light. In order to check the structure of

{\mathcal{H}}_{e}

, we have performed a detailed experimental study of the ground-state energy sublevels of various kinds of atoms perturbed by different types of nonresonant light beams. Attention is paid to the modification of the Zeeman structure due to

{\mathcal{H}}_{e}

. We have been able to obtain experimentally in the ground state of

^{199}\mathrm{Hg}

^{201}\mathrm{Hg}

, and

^{87}\mathrm{Rb}

, Zeeman light shifts that are larger than the width of the levels due to the thermal relaxation. The removal of the Zeeman degeneracy in zero external field, due to a nonresonant light irradiation, is observed by different optical-pumping techniques; the full Zeeman diagram of the perturbed atoms is also determined when a static field ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}}_{0}$ is added. We have checked that the effect of

{\mathcal{H}}_{e}

can be described in terms of fictitious static electric or magnetic fields. These fictitious fields can be used to act selectively on a given atomic level.