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

Journal of the Optical Society of America

Production of Narrow Balmer Spectrum Lines in an Electron-Bombarded Atomic Hydrogen Beam*

John O. Stoner

Published Nov 1, 1964• 2 citations
Publisher

Abstract

An apparatus is described which has produced and detected narrow Hβ and Hγ spectral lines in an electron-bombarded atomic hydrogen beam. Hydrogen atoms produced in an electrodeless 50-Mc/sec discharge in wet hydrogen, diffused through a slit in the discharge tube wall to form a beam in a vacuum chamber. An electron gun bombarded the atomic beam along an axis perpendicular to the beam and optical axes; light produced in the decay of atoms excited by the bombardment was analyzed by a pressure-scanned Fabry–Perot interferometer and detected by a cooled photomultiplier. The output pulses from the photomultiplier were amplified and then stored as counts in a 400-channel analyzer. Linewidths characteristic of a source at about 33°K were obtained; however, the signals were so small and the line shapes sufficiently uncertain that no precise wavelength measurements could be made.

DOI
10.1364/josa.54.001377

Related papers

Coherent excitation of the n=3 states in hydrogen

Robert V. Krotkov

This paper is a theoretical discussion of a "coherence effect" in the excitation of hydrogen atoms to the $n=3$ state by electron bombardment. By coherence is meant that the density matrix describing the atom after the collision has off-diagonal matrix elements in the field-free basis. The differential cross section for producing Balmer-$\ensuremath{\alpha}$ photons at 90\ifmmode^\circ\else\textdegree\fi{} to the electron beam is calculated as a function of an applied longitudinal electric field. The off-diagonal elements show up as a dependence of the observed light on the directions of the electric field. Theoretical results based on the Born approximation are compared with an experiment at 200 and 500 eV. It is pointed out that this method for measuring relative phases of scattering amplitudes can be generally applied and is not restricted to $n=3$ excitation of hydrogen.

Physical Review A•Nov 1, 1975•19 citations

Barrier-discharge source of cold hydrogen atoms in supersonic beams: Stark effect in the 1s–2s transition

Simon Scheidegger, David Schlander, Josef A. Agner +3 more

Abstract An intense source of cold hydrogen atoms in a supersonic beam is presented. H and D atoms are produced from pure samples of H2 and D2 using a barrier discharge near the orifice of a cryogenic pulsed valve. The atoms are entrained in the supersonic expansion of the precursor molecules and cool down to translational temperatures as low as ∼ 15 mK. The H-atom density at a distance of 1.2 m from the valve orifice is estimated to be around 108 cm−3. The mean velocity of the supersonic beam containing the H (D) atoms can be adjusted between 2600 and 1200 m s−1 (between 1850 and 820 m s−1). The barrier discharge also produces H n + and D n + ions with n ranging from 2 to 8, which can be deflected off the beam by electric fields. The use of this H-atom source in spectroscopic measurements is demonstrated by an investigation of the Stark effect in the 1s–2s two-photon transition of H and D. A near-Fourier-transform-limited pulsed laser generating pulses of UV radiation of adjustable pulse length between 10 and 200 ns near 243 nm is used to record spectra with full resolution of the hyperfine structure in the s states, providing a textbook example of the Stark effect in the simplest set of near-degenerate states of one-electron atoms.

Journal of Physics B Atomic Molecular and Optical Physics•Jun 2, 2022•6 citations

The Magnetic Moment of the Hydrogen Atom

T. E. Phipps, John Bradshaw Taylor

The magnetic moment of the hydrogen atom has been investigated by the atomic ray method introduced by Stern and Gerlach. Atomic hydrogen formed in a discharge tube by the method of R. W. Wood was first used. The ray was formed in a special all-glass slit system of three slits sealed to the discharge tube. The ray was detected by the reduction resulting on contact with a target coated with molybdenum trioxide. A sharply defined blue line against a white background was the result. In the magnetic field the ray was separated into two branching rays. There was also evidence of a central underviated ray which is believed to be due to hydrogen active chemically but probably not in the atomic state. From a measurement of the deflection the magnetic moment of the hydrogen atom was calculated to be one Bohr magneton within the limits of experimental error. This result is of interest because of the questions raised by the new quantum mechanics of Heisenberg, Born, and Jordan, and by the spinning electron theory of Uhlenbeck and Goudsmit. Atomic hydrogen formed by the hot filament method of Langmuir was next used. The increased velocity of the atoms in this case resulted in less separation of the ray, but a deflection was distinctly recorded. Finally, the product formed on exposing a mixture of mercury vapor and hydrogen to ultra-violet light was investigated. This is believed by Cario and Franck, Taylor, and others to be atomic hydrogen. Thus far attempts to form a ray which will reduce the target have been unsuccessful. The reasons for this are being investigated.

Physical Review•Feb 1, 1927•100 citations

Collisional production of fast metastable hydrogen atoms from cold H2: toward twin atoms

Aline Medina, G. Rahmat, C. R. de Carvalho +8 more

We have investigated the production of fast metastable H(2 2 S) coming from the dissociation of cold H 2 molecules produced in a Campargue nozzle beam after crossing with an electron beam emerging from a high intensity pulsed electron gun. We have achieved dissociation by electron impact in order to avoid limitations due to the selection rules governing radiative transitions. Two detectors, placed 230 and 254 mm away from the collision centre, have analysed the neutral fragments as a function of their time-of-flight through localized quenching of H(2 2 S) in H(2 2 P) and Lyman-α detection. Performing coincidence experiments in order to ascertain the existence of the H(2 2 S)–H(2 2 S) dissociation channel is appealing due to the anlysis of the spectra.

Journal of Physics B Atomic Molecular and Optical Physics•Oct 20, 2011•13 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

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
An apparatus is described which has produced and detected narrow Hβ and Hγ spectral lines in an electron-bombarded atomic hydrogen beam. Hydrogen atoms produced in an electrodeless 50-Mc/sec discharge in wet hydrogen, diffused through a slit in the discharge tube wall to form a beam in a vacuum chamber. An electron gun bombarded the atomic beam along an axis perpendicular to the beam and optical axes; light produced in the decay of atoms excited by the bombardment was analyzed by a pressure-scanned Fabry–Perot interferometer and detected by a cooled photomultiplier. The output pulses from the photomultiplier were amplified and then stored as counts in a 400-channel analyzer. Linewidths characteristic of a source at about 33°K were obtained; however, the signals were so small and the line shapes sufficiently uncertain that no precise wavelength measurements could be made.
This paper is a theoretical discussion of a "coherence effect" in the excitation of hydrogen atoms to the n=3n=3n=3 state by electron bombardment. By coherence is meant that the density matrix describing the atom after the collision has off-diagonal matrix elements in the field-free basis. The differential cross section for producing Balmer-$\ensuremath{\alpha}$ photons at 90\ifmmode^\circ\else\textdegree\fi{} to the electron beam is calculated as a function of an applied longitudinal electric field. The off-diagonal elements show up as a dependence of the observed light on the directions of the electric field. Theoretical results based on the Born approximation are compared with an experiment at 200 and 500 eV. It is pointed out that this method for measuring relative phases of scattering amplitudes can be generally applied and is not restricted to n=3n=3n=3 excitation of hydrogen.
Abstract An intense source of cold hydrogen atoms in a supersonic beam is presented. H and D atoms are produced from pure samples of H2 and D2 using a barrier discharge near the orifice of a cryogenic pulsed valve. The atoms are entrained in the supersonic expansion of the precursor molecules and cool down to translational temperatures as low as ∼ 15 mK. The H-atom density at a distance of 1.2 m from the valve orifice is estimated to be around 108 cm−3. The mean velocity of the supersonic beam containing the H (D) atoms can be adjusted between 2600 and 1200 m s−1 (between 1850 and 820 m s−1). The barrier discharge also produces H n + and D n + ions with n ranging from 2 to 8, which can be deflected off the beam by electric fields. The use of this H-atom source in spectroscopic measurements is demonstrated by an investigation of the Stark effect in the 1s–2s two-photon transition of H and D. A near-Fourier-transform-limited pulsed laser generating pulses of UV radiation of adjustable pulse length between 10 and 200 ns near 243 nm is used to record spectra with full resolution of the hyperfine structure in the s states, providing a textbook example of the Stark effect in the simplest set of near-degenerate states of one-electron atoms.
The magnetic moment of the hydrogen atom has been investigated by the atomic ray method introduced by Stern and Gerlach. Atomic hydrogen formed in a discharge tube by the method of R. W. Wood was first used. The ray was formed in a special all-glass slit system of three slits sealed to the discharge tube. The ray was detected by the reduction resulting on contact with a target coated with molybdenum trioxide. A sharply defined blue line against a white background was the result. In the magnetic field the ray was separated into two branching rays. There was also evidence of a central underviated ray which is believed to be due to hydrogen active chemically but probably not in the atomic state. From a measurement of the deflection the magnetic moment of the hydrogen atom was calculated to be one Bohr magneton within the limits of experimental error. This result is of interest because of the questions raised by the new quantum mechanics of Heisenberg, Born, and Jordan, and by the spinning electron theory of Uhlenbeck and Goudsmit. Atomic hydrogen formed by the hot filament method of Langmuir was next used. The increased velocity of the atoms in this case resulted in less separation of the ray, but a deflection was distinctly recorded. Finally, the product formed on exposing a mixture of mercury vapor and hydrogen to ultra-violet light was investigated. This is believed by Cario and Franck, Taylor, and others to be atomic hydrogen. Thus far attempts to form a ray which will reduce the target have been unsuccessful. The reasons for this are being investigated.
We have investigated the production of fast metastable H(2 2 S) coming from the dissociation of cold H 2 molecules produced in a Campargue nozzle beam after crossing with an electron beam emerging from a high intensity pulsed electron gun. We have achieved dissociation by electron impact in order to avoid limitations due to the selection rules governing radiative transitions. Two detectors, placed 230 and 254 mm away from the collision centre, have analysed the neutral fragments as a function of their time-of-flight through localized quenching of H(2 2 S) in H(2 2 P) and Lyman-α detection. Performing coincidence experiments in order to ascertain the existence of the H(2 2 S)–H(2 2 S) dissociation channel is appealing due to the anlysis of the spectra.
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.
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.