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

Review of Scientific Instruments

Metastable hydrogen atom detector suitable for time-of-flight studies

Stephen J. Czuchlewski, S. R. Ryan, William H. Wing

Published Sep 1, 1976• 10 citations
Publisher

Abstract

A selective detection scheme for atoms in the metastable 2s state of hydrogen that provides the high spatial resolution (0.1 cm) necessary for time-of-flight atomic-beam studies is described. The scheme utilizes the Lyman α photon emitted when the metastable is de-excited in an electric field via the Stark effect. Details of construction and operation are discussed.

DOI
10.1063/1.1134831

Related papers

Lyman-α radiation of a metastable hydrogen beam to measure electric fields

A. Lejeune, Laurence Chérigier-Kovacic, F. Doveil

The interaction between a metastable H(2s) atomic hydrogen beam and an external electric field leads to the emission of the Lyman-α line. It originates in the Stark mixing of the near-degenerate 2s1/2 and 2p1/2 levels separated by the Lamb shift. The quenched radiation proportional to the square of the electric field amplitude is recovered in vacuum by using such an atomic probe beam. We observe the strong enhancement of the signal when the field is oscillating at the Lamb shift frequency. This technique is applied in a plasma, offering an alternative way to measure weak electric fields by direct and non-intrusive means.

Applied Physics Letters•Oct 31, 2011•7 citations

Fast metastable hydrogen atoms from H2molecules: twin atoms

Azer Trimeche, David Houdoux, G. Rahmat +9 more

It is a difficult task to obtain “twin atoms”, i.e. pairs of massive particles such that one can perform experiments in the same fashion that is routinely done with “twin photons”. One possible route to obtain such pairs is by dissociating homonuclear diatomic molecules. We address this possibility by investigating the production of metastable H(2s) atoms coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam crossing an electron beam from a high intensity pulsed electron gun. Dissociation by electron impact was chosen to avoid limitations of target molecular excited states due to selection rules. Detectors placed several centimeters away from the collision center, and aligned with respect to possible common molecular dissociation channel, analyze the neutral fragments as a function of their time-of-flight (TOF) through Lyman-α detection. Evidence for the first time observed coincidence of pairs of H(2s) atoms obtained this way is presented.

EPJ Web of Conferences•Jan 1, 2015•0 citations

Slow metastable atomic hydrogen beam by optical pumping

Kenneth C. Harvey

A beam source of atomic hydrogen is described which produces metastable atoms in the 2S1/2 state by optical pumping. A beam flux of 1016 atoms/s is generated in the ground state. The atoms in the beam pass in front of a lamp producing Lyman-β (1026 Å) radiation, where some of them are excited to the 3P level and cascade with a branching ratio of 12% to the 2S1/2 state. The number of metastable atoms produced is measured by quenching them with an electric field and detecting the emitted Lyman-α (1216 Å) radiation. Beams of 106 metastable atoms/s were obtained. Using the Bethe-Lamb theory for the quenching process, a metastable beam effective temperature of 100 K was measured.

Journal of Applied Physics•May 1, 1982•17 citations

Lyman-α radiation of a probing metastable hydrogen beam to measure electric fields in diluted fluids and plasmas

F. Doveil, A. Lejeune, Laurence Chérigier-Kovacic

The interaction between a metastable H(2s) atomic hydrogen beam and an external electric field leads to the emission of the Lyman-α line. It originates in the Stark mixing of the near-degenerate 2s1/2 and 2p1/2 levels separated by the Lamb shift. The quenched radiation proportional to the square of the electric field amplitude is recovered in vacuum by using such an atomic probe beam. For larger electric field, saturation is observed and related to the beam finite transit time. We also observe the strong enhancement of the signal when the field is oscillating at the Lamb shift frequency. This technique is applied in a plasma, offering an alternative way to measure weak electric fields by direct and non-intrusive means.

Physics of Plasmas•Apr 15, 2013•5 citations

Polarization of Lyman Alpha-Radiation Emitted in Electron-Hydrogen Atom Collisions and Emitted by Metastable H(2S) Atoms in Weak Electric Fields.

William R. Ott

•Jan 1, 1968•0 citations

Detection of nitrogen atoms in the 2s(2p)$sup 3$3s $sup 6$S/sub 5/2/ metastable autoionizing state

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

Metastable nitrogen atoms, produced by electron-impact dissociation of N/ sub 2/, have been detected in time-of-flight apparatuses locatcd at Oregon State University and at University of California at Berkeley. Two different types of metastable atoms are detected; one type resembies Rydberg hydrogen atoms, while the other does not. The measured natural lifetime for the non-Rydberg atoms is 100 plus or minus 25 mu see. Additional infonnation 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-Rydherg 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 x 10/sup 6/ sec/sup -1/. The quenching results, together with the lifetime measurement, are a strong more » indication that the non-Rydberg atoms detected in the time-of-flight spectra are nitrogen atoms in the 2s(2p)/sup 3/3s /sup 6/S/sub 5/2/ metastable autoionizing state. (a uth) « less

Physical Review A•Aug 1, 1973•0 citations
A selective detection scheme for atoms in the metastable 2s state of hydrogen that provides the high spatial resolution (0.1 cm) necessary for time-of-flight atomic-beam studies is described. The scheme utilizes the Lyman α photon emitted when the metastable is de-excited in an electric field via the Stark effect. Details of construction and operation are discussed.
The interaction between a metastable H(2s) atomic hydrogen beam and an external electric field leads to the emission of the Lyman-α line. It originates in the Stark mixing of the near-degenerate 2s1/2 and 2p1/2 levels separated by the Lamb shift. The quenched radiation proportional to the square of the electric field amplitude is recovered in vacuum by using such an atomic probe beam. We observe the strong enhancement of the signal when the field is oscillating at the Lamb shift frequency. This technique is applied in a plasma, offering an alternative way to measure weak electric fields by direct and non-intrusive means.
It is a difficult task to obtain “twin atoms”, i.e. pairs of massive particles such that one can perform experiments in the same fashion that is routinely done with “twin photons”. One possible route to obtain such pairs is by dissociating homonuclear diatomic molecules. We address this possibility by investigating the production of metastable H(2s) atoms coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam crossing an electron beam from a high intensity pulsed electron gun. Dissociation by electron impact was chosen to avoid limitations of target molecular excited states due to selection rules. Detectors placed several centimeters away from the collision center, and aligned with respect to possible common molecular dissociation channel, analyze the neutral fragments as a function of their time-of-flight (TOF) through Lyman-α detection. Evidence for the first time observed coincidence of pairs of H(2s) atoms obtained this way is presented.
A beam source of atomic hydrogen is described which produces metastable atoms in the 2S1/2 state by optical pumping. A beam flux of 1016 atoms/s is generated in the ground state. The atoms in the beam pass in front of a lamp producing Lyman-β (1026 Å) radiation, where some of them are excited to the 3P level and cascade with a branching ratio of 12% to the 2S1/2 state. The number of metastable atoms produced is measured by quenching them with an electric field and detecting the emitted Lyman-α (1216 Å) radiation. Beams of 106 metastable atoms/s were obtained. Using the Bethe-Lamb theory for the quenching process, a metastable beam effective temperature of 100 K was measured.
The interaction between a metastable H(2s) atomic hydrogen beam and an external electric field leads to the emission of the Lyman-α line. It originates in the Stark mixing of the near-degenerate 2s1/2 and 2p1/2 levels separated by the Lamb shift. The quenched radiation proportional to the square of the electric field amplitude is recovered in vacuum by using such an atomic probe beam. For larger electric field, saturation is observed and related to the beam finite transit time. We also observe the strong enhancement of the signal when the field is oscillating at the Lamb shift frequency. This technique is applied in a plasma, offering an alternative way to measure weak electric fields by direct and non-intrusive means.
Detection of nitrogen atoms in the 2s(2p)$sup 3$3s sup6sup 6sup6S/sub 5/2/ metastable autoionizing state
Metastable nitrogen atoms, produced by electron-impact dissociation of N/ sub 2/, have been detected in time-of-flight apparatuses locatcd at Oregon State University and at University of California at Berkeley. Two different types of metastable atoms are detected; one type resembies Rydberg hydrogen atoms, while the other does not. The measured natural lifetime for the non-Rydberg atoms is 100 plus or minus 25 mu see. Additional infonnation 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-Rydherg 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 x 10/sup 6/ sec/sup -1/. The quenching results, together with the lifetime measurement, are a strong more » indication that the non-Rydberg atoms detected in the time-of-flight spectra are nitrogen atoms in the 2s(2p)/sup 3/3s /sup 6/S/sub 5/2/ metastable autoionizing state. (a uth) « less