Physical Review A

gJ factor of metastable S25 atomic oxygen using a time-of-flight, atomic-beam magnetic-resonance method

Tuncay Incesu, Ahsanul Huq, Howard A. Shugart

Published Sep 1, 1978• 1 citation

Abstract

A time-of-flight, atomic-beam magnetic-resonance method was used to compare the ${g}_{J}$ factor of $2{p}^{3}3s^{5}S_{2}$ atomic oxygen with the ${g}_{J}$ factor of metastable $2^{3}S_{1}$ atomic helium in magnetic fields of 3209 and 4228 G. The metastable oxygen and helium atoms were produced in a pulsed radio-frequency discharge source and after traversing the apparatus were detected by electron emission from a tungsten surface. By collecting data only in a given interval of the time-of-flight distribution the $\mathrm{O}(^{5}S)$ and $\mathrm{He}(^{3}S)$ states were isolated from other discharge products. From 158 pairs of resonances taken with four relative field and hairpin orientations the atomic magnetic $g$ factor is ${g}_{J}(^{5}S_{2}, ^{16}\mathrm{O})=\frac{{\ensuremath{\mu}}_{J}}{J}=\ensuremath{-}2.0020910(10)$.

DOI: 10.1103/physreva.18.797

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Physical Review A

gJ factor of metastable S25 atomic oxygen using a time-of-flight, atomic-beam magnetic-resonance method

Tuncay Incesu, Ahsanul Huq, Howard A. Shugart

Published Sep 1, 1978• 1 citation

Publisher

Abstract

A time-of-flight, atomic-beam magnetic-resonance method was used to compare the

{g}_{J}

factor of

2{p}^{3}3s^{5}S_{2}

atomic oxygen with the

{g}_{J}

factor of metastable

2^{3}S_{1}

atomic helium in magnetic fields of 3209 and 4228 G. The metastable oxygen and helium atoms were produced in a pulsed radio-frequency discharge source and after traversing the apparatus were detected by electron emission from a tungsten surface. By collecting data only in a given interval of the time-of-flight distribution the

\mathrm{O}(^{5}S)

and

\mathrm{He}(^{3}S)

states were isolated from other discharge products. From 158 pairs of resonances taken with four relative field and hairpin orientations the atomic magnetic

g

factor is

{g}_{J}(^{5}S_{2}, ^{16}\mathrm{O})=\frac{{\ensuremath{\mu}}_{J}}{J}=\ensuremath{-}2.0020910(10)

DOI: 10.1103/physreva.18.797

Related papers

Radiative Lifetime of the 2 S01 Metastable State of Helium

Robert S. Van Dyck, C. E. Johnson, Howard A. Shugart

A time-of-flight technique has been used to measure the radiative lifetime of the $2 ^{1}S_{0}$ state of helium. After passing from a cooled source, helium atoms are excited by a pulsed anti-parallel electron beam. The atomic beam then contains not only ground-state helium atoms but also metastable atoms in both the $2 ^{3}S_{1}$ and the $2 ^{1}S_{0}$ states. The metastable atoms are detected at two positions, 1.9 and 6.7 m from the electron gun, by Auger ejection of an electron from a copper target, the first of which is a 60% transmitting mesh. Ground-state helium atoms cannot cause an electron to be ejected and hence are not detected. The time-of-flight distribution for the metastable $2 ^{1}S_{0}$ state is separated from that of the $2 ^{3}S_{1}$ state by illuminating the beam with an rf-discharge helium lamp. The $2 ^{1}S_{0}$ state is quenched by resonant absorption of a 20 581 - \AA{}A photon, raising the atom to the $2 ^{1}P_{1}$ state, which then decays preferentially to the $^{1}S_{0}$ ground state; the $2 ^{3}S_{1}$ state remains unaffected because it is the ground state for the triplet system. The time-of-flight distribution for the $2 ^{1}S_{0}$ atoms is therefore obtained from the difference between the full beam and the quenched beam. A comparison of the number of $2 ^{1}S_{0}$ metastables within a given velocity interval at the two detectors determines the number which decay in flight and yields a value for the two-photon radiative lifetime. The value of the singlet lifetime for both ${\mathrm{He}}^{3}$ and ${\mathrm{He}}^{4}$ is 19.7 \ifmmode\pm\else\textpm\fi{} 1.0 msec, agreeing with the theoretical value of 19.5 msec, but disagreeing with the value 38 \ifmmode\pm\else\textpm\fi{} 8 msec measured by Pearl using a movable detector. The 1.0-msec error is an estimate of the remaining systematic errors in the experiment.A time-of-flight technique has been used to measure the radiative lifetime of the $2 ^{1}S_{0}$ state of helium. After passing from a cooled source, helium atoms are excited by a pulsed anti-parallel electron beam. The atomic beam then contains not only ground-state helium atoms but also metastable atoms in both the $2 ^{3}S_{1}$ and the $2 ^{1}S_{0}$ states. The metastable atoms are detected at two positions, 1.9 and 6.7 m from the electron gun, by Auger ejection of an electron from a copper target, the first of which is a 60% transmitting mesh. Ground-state helium atoms cannot cause an electron to be ejected and hence are not detected. The time-of-flight distribution for the metastable $2 ^{1}S_{0}$ state is separated from that of the $2 ^{3}S_{1}$ state by illuminating the beam with an rf-discharge helium lamp. The $2 ^{1}S_{0}$ state is quenched by resonant absorption of a 20 581 - \AA{}A photon, raising the atom to the $2 ^{1}P_{1}$ state, which then decays preferentially to the $^{1}S_{0}$ ground state; the $2 ^{3}S_{1}$ state remains unaffected because it is the ground state for the triplet system. The time-of-flight distribution for the $2 ^{1}S_{0}$ atoms is therefore obtained from the difference between the full beam and the quenched beam. A comparison of the number of $2 ^{1}S_{0}$ metastables within a given velocity interval at the two detectors determines the number which decay in flight and yields a value for the two-photon radiative lifetime. The value of the singlet lifetime for both ${\mathrm{He}}^{3}$ and ${\mathrm{He}}^{4}$ is 19.7 \ifmmode\pm\else\textpm\fi{} 1.0 msec, agreeing with the theoretical value of 19.5 msec, but disagreeing with the value 38 \ifmmode\pm\else\textpm\fi{} 8 msec measured by Pearl using a movable detector. The 1.0-msec error is an estimate of the remaining systematic errors in the experiment.

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Quenching of the 2S01 Metastable State of Helium by an Electric Field

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Experimental gJ factor in the metastable 5 D3/2 level of Ba+

K. H. Knöll, G. Marx, K. Hübner +4 more

The Zeeman splitting of the metastable 5 ${\mathit{D}}_{3/2}$ level of $^{138}\mathrm{Ba}^{+}$ in a magnetic field of 6 T has been measured in a laser-microwave double resonance experiment in a Penning ion trap. The magnetic field at the ion's position is determined by the cyclotron frequency of electrons stored in the same trap. From the ratio of both transition frequencies we obtain a ${\mathit{g}}_{\mathit{J}}$ value of 0.799 327 8(3). As a by-product, we confirmed earlier measurements on the 6 ${\mathit{S}}_{1/2}$ ground-state ${\mathit{g}}_{\mathit{J}}$ factor to 2.002 492 2(10). The precision in both experiments is sufficient to test relativistic many-body calculations. \textcopyright{} 1996 The American Physical Society.The Zeeman splitting of the metastable 5${\mathit{D}}_{3/2}$ level of $^{138}\mathrm{Ba}^{+}$ in a magnetic field of 6 T has been measured in a laser-microwave double resonance experiment in a Penning ion trap. The magnetic field at the ion's position is determined by the cyclotron frequency of electrons stored in the same trap. From the ratio of both transition frequencies we obtain a ${\mathit{g}}_{\mathit{J}}$ value of 0.799 327 8(3). As a by-product, we confirmed earlier measurements on the 6${\mathit{S}}_{1/2}$ ground-state ${\mathit{g}}_{\mathit{J}}$ factor to 2.002 492 2(10). The precision in both experiments is sufficient to test relativistic many-body calculations. \textcopyright{} 1996 The American Physical Society.

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g Factors of the 6s5d Configuration of Atomic Barium

Gilbert O. Brink, Robert J. Hull

The four metastable states of atomic barium comprising the $6s5d$ configuration have been studied by atomic-beam magnetic resonance, and information concerning their $g$ factors has been obtained. Data from this work agree with that obtained recently by v. Oppen using a different method, and agreement is also obtained with theory.The four metastable states of atomic barium comprising the $6s5d$ configuration have been studied by atomic-beam magnetic resonance, and information concerning their $g$ factors has been obtained. Data from this work agree with that obtained recently by v. Oppen using a different method, and agreement is also obtained with theory.

Physical ReviewMar 5, 19695 citations

A time-of-flight, atomic-beam magnetic-resonance method was used to compare the

{g}_{J}

factor of

2{p}^{3}3s^{5}S_{2}

atomic oxygen with the

{g}_{J}

factor of metastable

2^{3}S_{1}

\mathrm{O}(^{5}S)

and

\mathrm{He}(^{3}S)

states were isolated from other discharge products. From 158 pairs of resonances taken with four relative field and hairpin orientations the atomic magnetic

g

factor is

{g}_{J}(^{5}S_{2}, ^{16}\mathrm{O})=\frac{{\ensuremath{\mu}}_{J}}{J}=\ensuremath{-}2.0020910(10)

A time-of-flight technique has been used to measure the radiative lifetime of the

2 ^{1}S_{0}

state of helium. After passing from a cooled source, helium atoms are excited by a pulsed anti-parallel electron beam. The atomic beam then contains not only ground-state helium atoms but also metastable atoms in both the

2 ^{3}S_{1}

and the

2 ^{1}S_{0}

states. The metastable atoms are detected at two positions, 1.9 and 6.7 m from the electron gun, by Auger ejection of an electron from a copper target, the first of which is a 60% transmitting mesh. Ground-state helium atoms cannot cause an electron to be ejected and hence are not detected. The time-of-flight distribution for the metastable

2 ^{1}S_{0}

state is separated from that of the

2 ^{3}S_{1}

state by illuminating the beam with an rf-discharge helium lamp. The

2 ^{1}S_{0}

state is quenched by resonant absorption of a 20 581 - \AA{}A photon, raising the atom to the

2 ^{1}P_{1}

state, which then decays preferentially to the

^{1}S_{0}

ground state; the

2 ^{3}S_{1}

state remains unaffected because it is the ground state for the triplet system. The time-of-flight distribution for the

2 ^{1}S_{0}

atoms is therefore obtained from the difference between the full beam and the quenched beam. A comparison of the number of

2 ^{1}S_{0}

metastables within a given velocity interval at the two detectors determines the number which decay in flight and yields a value for the two-photon radiative lifetime. The value of the singlet lifetime for both

{\mathrm{He}}^{3}

and

{\mathrm{He}}^{4}

is 19.7 \ifmmode\pm\else\textpm\fi{} 1.0 msec, agreeing with the theoretical value of 19.5 msec, but disagreeing with the value 38 \ifmmode\pm\else\textpm\fi{} 8 msec measured by Pearl using a movable detector. The 1.0-msec error is an estimate of the remaining systematic errors in the experiment.

A time-of-flight technique has been used to measure the quenching of the

2^{1}S_{0}

metastable state of helium by a static electric field. Neutral ground-state helium atoms effusing from a cooled source slit are immediately excited to the

2^{1}S_{0}

and

2^{3}S_{1}

metastable states by a pulse of antiparallel magnetically focused electrons. The metastable beam is collimated before passing through a uniform electric field region 0.5 m long and is then preferentially detected at the end of the time-of-flight region, 1.825 m from the electron gun. The time-of-flight distribution for the

2^{1}S_{0}

state is separated from that of the

2^{3}S_{1}

state by illuminating the beam before the electric field region with an rf-discharge helium lamp. The

2^{1}S_{0}

state is quenched by resonant absorption of a 20 581-\AA{} photon, raising the atom to the

2^{1}P_{1}

state, which then decays to the

^{1}S_{0}

ground state; the

2^{3}S_{1}

state remains unaffected because it is the ground state for the triplet system. The

2^{1}S_{0}

time-of-flight distribution is therefore obtained from the difference between the full beam and the quenched beam. The number of

2^{1}S_{0}

atoms arriving at the detector in specific velocity intervals with the electric field off is compared to the number with the field on to determine the quenching rate (

=k{E}^{2}

). The result for the quenching constant

k

for both

{\mathrm{He}}^{3}

and

{\mathrm{He}}^{4}

with

E

in kV/cm is $k=0.933\ifmmode\pm\else\textpm\fi{}0.005$; this value is in good agreement with theory and with an earlier less accurate experiment. The error in the present experiment arises from a 0.5% uncertainty in the effective length of the electric field region.

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.

The Zeeman splitting of the metastable 5

{\mathit{D}}_{3/2}

level of

^{138}\mathrm{Ba}^{+}

in a magnetic field of 6 T has been measured in a laser-microwave double resonance experiment in a Penning ion trap. The magnetic field at the ion's position is determined by the cyclotron frequency of electrons stored in the same trap. From the ratio of both transition frequencies we obtain a

{\mathit{g}}_{\mathit{J}}

value of 0.799 327 8(3). As a by-product, we confirmed earlier measurements on the 6

{\mathit{S}}_{1/2}

ground-state

{\mathit{g}}_{\mathit{J}}

factor to 2.002 492 2(10). The precision in both experiments is sufficient to test relativistic many-body calculations. \textcopyright{} 1996 The American Physical Society.

The four metastable states of atomic barium comprising the

6s5d

configuration have been studied by atomic-beam magnetic resonance, and information concerning their

g

factors has been obtained. Data from this work agree with that obtained recently by v. Oppen using a different method, and agreement is also obtained with theory.