Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review A

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

Charles E. Johnson

Published Mar 1, 1973• 10 citations
Publisher

Abstract

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.

DOI
10.1103/physreva.7.872

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.

Physical Review A•Oct 1, 1971•99 citations

Electric Field Quenching of Metastable 2S01 Helium

Richard D. Petrasso, A.T. Ramsey

We have measured the transition rate of the normally metastable helium $2^{1}S_{0}$ state in the presence of a uniform electric field by observing the attenuation of a metastable beam of helium passing between parallel electric field plates. This attenuation, when combined with our measurement of the velocity distribution of the beam, yields a transition rate of $(0.926\ifmmode\pm\else\textpm\fi{}0.020){F}^{2}$ ${\mathrm{sec}}^{\ensuremath{-}1}$, where $F$ is the field strength in kV/cm. This agrees well with our calculated value of $(0.920\ifmmode\pm\else\textpm\fi{}0.030){F}^{2}$ ${\mathrm{sec}}^{\ensuremath{-}1}$ which is derived from a sum of oscillator strengths published by various workers.

Physical Review A•Jan 1, 1972•10 citations

Dipole polarizability of 2S13 and 2S01 metastable helium measured by the electric deflection time-of-flight method

David A. Crosby, Jens C. Zorn

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.

Physical Review A•Aug 1, 1977•25 citations

Optical Quenching of Metastable Helium Atoms using Excitation to the 4P State

Jiwen Guan, Vivien Behrendt, Pinrui Shen +5 more

The optical pumping of atoms is a central process in many applications of atomic physics, such as laser cooling and the precise determination of physical constants. Popular methods for producing metastable helium atoms in supersonic expansions are discharge and electron-impact excitation. However, both approaches yield helium atoms in two metastable states, ${2}^{1}{S}_{0}$ and ${2}^{3}{S}_{1}$, which limits the applications of these highly energetic species. This study presents an experimental scheme in which the ${2}^{1}{S}_{0}$ state population is depleted via excitation to the ${4}^{1}{P}_{1}$ state, using diode-laser radiation. The results suggest nearly 100% depletion efficiency at all beam velocities studied.

arXiv:1906.06731•Physical Review Applied•May 28, 2019•8 citations

Radiative Lifetime of the Metastable 2S01 State of Helium

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

Two fixed, spatially separated detectors are used to measure the decay in flight of a cooled, thermal beam of pulsed metastable helium atoms. The preliminary value obtained for the radiative lifetime of the metastable $2^{1}S_{0}$ state of helium is 20 \ifmmode\pm\else\textpm\fi{} 2 msec.

Physical Review Letters•Nov 16, 1970•38 citations

Detection of Nitrogen Atoms in the 2s(2p)33sS526 Metastable Autoionizing State

Clifford E. Fairchild, Hari Prasad Garg, C. E. Johnson

Metastable nitrogen atoms, produced by electron-impact dissociation of ${\mathrm{N}}_{2}$, have been detected in time-of-flight apparatuses located at Oregon State University and at University of California at Berkeley. Two different types of metastable atoms are detected; one type resembles Rydberg hydrogen atoms, while the other does not. The measured natural lifetime for the non-Rydberg atoms is 100 \ifmmode\pm\else\textpm\fi{} 25 \ensuremath{\mu}sec. Additional information regarding the identity of both types of metastable atoms is obtained by observing their quenching in a static electric field. The field-dependent decay constant for the Rydberg atoms is essentially a step function, and these atoms are entirely quenched by a field of 1.5 kV/cm. Both results are consistent with theory if the Rydberg atoms are in levels with principal quantum number greater than 25. The field-dependent decay constant for the non-Rydberg atoms varies quadratically with the strength of the applied electric field. In a field of 4 kV/cm applied along a 6-cm length of flight path, the value of this decay constant is 0.3 \ifmmode\times\else\texttimes\fi{} ${10}^{6}$ ${\mathrm{sec}}^{\ensuremath{-}1}$. The quenching results, together with the lifetime measurement, are a strong indication that the non-Rydberg atoms detected in the time-of-flight spectra are nitrogen atoms in the $2s{(2p)}^{3}3s^{6}S_{\frac{5}{2}}$ metastable autoionizing state.

Physical Review A•Aug 1, 1973•7 citations
A time-of-flight technique has been used to measure the quenching of the 21S02^{1}S_{0}21S0​ 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 21S02^{1}S_{0}21S0​ and 23S12^{3}S_{1}23S1​ 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 21S02^{1}S_{0}21S0​ state is separated from that of the 23S12^{3}S_{1}23S1​ state by illuminating the beam before the electric field region with an rf-discharge helium lamp. The 21S02^{1}S_{0}21S0​ state is quenched by resonant absorption of a 20 581-\AA{} photon, raising the atom to the 21P12^{1}P_{1}21P1​ state, which then decays to the 1S0^{1}S_{0}1S0​ ground state; the 23S12^{3}S_{1}23S1​ state remains unaffected because it is the ground state for the triplet system. The 21S02^{1}S_{0}21S0​ time-of-flight distribution is therefore obtained from the difference between the full beam and the quenched beam. The number of 21S02^{1}S_{0}21S0​ 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 (=kE2=k{E}^{2}=kE2). The result for the quenching constant kkk for both He3{\mathrm{He}}^{3}He3 and He4{\mathrm{He}}^{4}He4 with EEE in kV/cm is k=0.933\ifmmode±\else\textpm\fi0.005k=0.933\ifmmode\pm\else\textpm\fi{}0.005k=0.933\ifmmode±\else\textpm\fi0.005; 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.
A time-of-flight technique has been used to measure the radiative lifetime of the 21S02 ^{1}S_{0}21S0​ 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 23S12 ^{3}S_{1}23S1​ and the 21S02 ^{1}S_{0}21S0​ 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 21S02 ^{1}S_{0}21S0​ state is separated from that of the 23S12 ^{3}S_{1}23S1​ state by illuminating the beam with an rf-discharge helium lamp. The 21S02 ^{1}S_{0}21S0​ state is quenched by resonant absorption of a 20 581 - \AA{}A photon, raising the atom to the 21P12 ^{1}P_{1}21P1​ state, which then decays preferentially to the 1S0^{1}S_{0}1S0​ ground state; the 23S12 ^{3}S_{1}23S1​ state remains unaffected because it is the ground state for the triplet system. The time-of-flight distribution for the 21S02 ^{1}S_{0}21S0​ atoms is therefore obtained from the difference between the full beam and the quenched beam. A comparison of the number of 21S02 ^{1}S_{0}21S0​ 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 He3{\mathrm{He}}^{3}He3 and He4{\mathrm{He}}^{4}He4 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.
We have measured the transition rate of the normally metastable helium 21S02^{1}S_{0}21S0​ state in the presence of a uniform electric field by observing the attenuation of a metastable beam of helium passing between parallel electric field plates. This attenuation, when combined with our measurement of the velocity distribution of the beam, yields a transition rate of $(0.926\ifmmode\pm\else\textpm\fi{}0.020){F}^{2}$ ${\mathrm{sec}}^{\ensuremath{-}1}$, where FFF is the field strength in kV/cm. This agrees well with our calculated value of $(0.920\ifmmode\pm\else\textpm\fi{}0.030){F}^{2}$ ${\mathrm{sec}}^{\ensuremath{-}1}$ which is derived from a sum of oscillator strengths published by various workers.
The static dipole polarizability of helium atoms in the metastable 23S12^{3}S_{1}23S1​ and 21S02^{1}S_{0}21S0​ 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, $\ensuremath{\alpha}(2^{3}S_{1})=(44.6\ifmmode\pm\else\textpm\fi{}3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}$ cm3{\mathrm{cm}}^{3}cm3 and $\ensuremath{\alpha}(2^{1}S_{0})=(108\ifmmode\pm\else\textpm\fi{}13)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}$ cm3{\mathrm{cm}}^{3}cm3, agree with the theoretical value that has been used to calibrate earlier polarizability measurements of the alkali metals and the heavier noble gases.
The optical pumping of atoms is a central process in many applications of atomic physics, such as laser cooling and the precise determination of physical constants. Popular methods for producing metastable helium atoms in supersonic expansions are discharge and electron-impact excitation. However, both approaches yield helium atoms in two metastable states, 21S0{2}^{1}{S}_{0}21S0​ and 23S1{2}^{3}{S}_{1}23S1​, which limits the applications of these highly energetic species. This study presents an experimental scheme in which the 21S0{2}^{1}{S}_{0}21S0​ state population is depleted via excitation to the 41P1{4}^{1}{P}_{1}41P1​ state, using diode-laser radiation. The results suggest nearly 100% depletion efficiency at all beam velocities studied.
Two fixed, spatially separated detectors are used to measure the decay in flight of a cooled, thermal beam of pulsed metastable helium atoms. The preliminary value obtained for the radiative lifetime of the metastable 21S02^{1}S_{0}21S0​ state of helium is 20 \ifmmode\pm\else\textpm\fi{} 2 msec.
Metastable nitrogen atoms, produced by electron-impact dissociation of N2{\mathrm{N}}_{2}N2​, have been detected in time-of-flight apparatuses located at Oregon State University and at University of California at Berkeley. Two different types of metastable atoms are detected; one type resembles Rydberg hydrogen atoms, while the other does not. The measured natural lifetime for the non-Rydberg atoms is 100 \ifmmode\pm\else\textpm\fi{} 25 \ensuremath{\mu}sec. Additional information regarding the identity of both types of metastable atoms is obtained by observing their quenching in a static electric field. The field-dependent decay constant for the Rydberg atoms is essentially a step function, and these atoms are entirely quenched by a field of 1.5 kV/cm. Both results are consistent with theory if the Rydberg atoms are in levels with principal quantum number greater than 25. The field-dependent decay constant for the non-Rydberg atoms varies quadratically with the strength of the applied electric field. In a field of 4 kV/cm applied along a 6-cm length of flight path, the value of this decay constant is 0.3 \ifmmode\times\else\texttimes\fi{} 106{10}^{6}106 ${\mathrm{sec}}^{\ensuremath{-}1}$. The quenching results, together with the lifetime measurement, are a strong indication that the non-Rydberg atoms detected in the time-of-flight spectra are nitrogen atoms in the 2s(2p)33s6S522s{(2p)}^{3}3s^{6}S_{\frac{5}{2}}2s(2p)33s6S25​​ metastable autoionizing state.