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

The Journal of Physical Chemistry A

A Mechanical Means to Produce Intense Beams of Slow Molecules

Manish Gupta, Dudley R. Herschbach

Published Nov 30, 1999• 108 citations
Publisher

Abstract

The flow velocity of gas emerging from a supersonic nozzle mounted on a high-speed rotor can be largely canceled by the rotor velocity, thereby producing an intense beam of molecules traveling in a vacuum with translational speeds slowed to a few tens of meters per second. Centrifugal action significantly enhances the supersonic character of the gas flow from the rotating nozzle, further narrowing the spread of velocities in the emerging beam. These features are demonstrated by model calculations and experimental results for beams of Xe and for O 2 and CH 3 F seeded in Xe.

DOI
10.1021/jp993560x

Related papers

Pulsed rotating supersonic source for merged molecular beams

Les Sheffield, Mark Hickey, V. B. Krasovitskiy +3 more

We describe a pulsed rotating supersonic beam source, evolved from an ancestral device [M. Gupta and D. Herschbach, J. Phys. Chem. A 105, 1626 (2001)]. The beam emerges from a nozzle near the tip of a hollow rotor which can be spun at high-speed to shift the molecular velocity distribution downward or upward over a wide range. Here we consider mostly the slowing mode. Introducing a pulsed gas inlet system, cryocooling, and a shutter gate eliminated the main handicap of the original device in which continuous gas flow imposed high background pressure. The new version provides intense pulses, of duration 0.1-0.6 ms (depending on rotor speed) and containing ∼10(12) molecules at lab speeds as low as 35 m/s and ∼10(15) molecules at 400 m∕s. Beams of any molecule available as a gas can be slowed (or speeded); e.g., we have produced slow and fast beams of rare gases, O(2), Cl(2), NO(2), NH(3), and SF(6). For collision experiments, the ability to scan the beam speed by merely adjusting the rotor is especially advantageous when using two merged beams. By closely matching the beam speeds, very low relative collision energies can be attained without making either beam very slow.

arXiv:1204.1029•Review of Scientific Instruments•Jun 1, 2012•9 citations

Velocity Augmentation of a Supersonic Source and The Production of Slow, Cold, Molecular Beams

Les Sheffield

In this thesis I describe the second generation of a rotating supersonic beam source. The purpose of this device is to produce velocity augmented molecular beams for use with scattering experiments or subsequent slowing methods. The beam emerges from a nozzle inserted at the tip of a hollow aluminum rotor which can be spun at high speeds in either the forward or backwards direction. The forward direction mode increases the laboratory frame velocity distribution of the emitted beam and the backward direction mode decreases this velocity distribution.\n\nBoth rotor modes are analyzed theoretically and experimentally within the text. I introduce a pulsed gas inlet system for the rotating source as well as cryocooling of the vacuum chamber. This new version provides moderately intense beams of slow molecules, containing ∼1012 molecules at lab speeds as low as 35 m/s, and very intense beams of fast molecules, containing ∼1015 molecules at 400 m/s. Beams of any molecule available in gas phase can be produced utilizing this system. For collision experiments, the ability to scan the velocity utilizing the rotating source is very advantageous when using two merged beams. If the two velocities can be closely matched, very low relative collision energies can be produced without making either beam slow.

•Feb 16, 2015•1 citation

Improved setup for producing slow beams of cold molecules using a rotating nozzle

M. Strebel, Frank Stienkemeier, Marcel Carto Constantin Mudrich

Intense beams of cold and slow molecules are produced by supersonic expansion out of a rapidly rotating nozzle, as first demonstrated by M. Gupta and D. Herschbach [J. Phys. Chem. A 103, 10670 (1999); 105, 1626 (2001)]. An improved setup is presented that is able to accelerate or decelerate cold atomic and molecular beams by up to 500 m/s. Technical improvements are discussed and beam parameters are characterized by detailed analysis of time-of-flight density distributions. The possibility of combining this beam source with electrostatic fields for guiding polar molecules is demonstrated.

arXiv:0910.3278•Physical Review A•Mar 17, 2010•38 citations

Production of high density molecular beams with wide velocity scanning

Les Sheffield, Sung Oh Woo, K. D. D. Rathnayaka +2 more

We describe modifications of a pulsed rotating supersonic beam source that improve performance, particularly increasing the beam density and sharpening the pulse profiles. As well as providing the familiar virtues of a supersonic molecular beam (high intensity, narrowed velocity distribution, and drastic cooling of rotation and vibration), the rotating source enables scanning the translational velocity over a wide range. Thereby, beams of any atom or molecule available as a gas can be slowed or speeded. Using Xe beams in the slowing mode, we have obtained lab speeds down to about 40 ± 5 m/s with density near 10(11) cm(-3) and in the speeding mode lab speeds up to about 660 m/s and density near 10(14) cm(-3). We discuss some congenial applications. Providing low lab speeds can markedly enhance experiments using electric or magnetic fields to deflect, steer, or further slow polar or paramagnetic molecules. The capability to scan molecular speeds facilitates merging velocities with a codirectional partner beam, enabling study of collisions at very low relative kinetic energies, without requiring either beam to be slow.

Review of Scientific Instruments•Jun 1, 2016•2 citations

A High Intensity Cold Atom Source

Jeremy Glick, William Huntington, Daniel J. Heinzen

A method for producing a high intensity cold atomic beam is discussed. The method is based on post-nozzle seeding of lithium into a supersonic helium jet.

•Jan 1, 2024•0 citations

Slowing and Speeding Molecular Beams by Means of a Rapidly Rotating Source

Manish Gupta, Dudley R. Herschbach

Mounting a molecular beam source near the tip of a hollow high-speed rotor provides a means to shift the velocity distribution of the beam downward or upward over a wide range. We describe the construction of such a device and experiments and model calculations characterizing its operation, for both supersonic and effusive beams of rare gases, O 2, CH 3 F, and SF 6 . For example, the flow velocity of a rotating supersonic beam of O 2 was accelerated to above 1000 m/s (corresponding to a kinetic energy of 2200 K and deBroglie wavelength of 0.1 Å) and decelerated (when seeded in Xe) to below 70 m/s (corresponding to a kinetic energy below 10 K and deBroglie wavelength of nearly 2 Å). With improvements in prospect, the rotating beam source offers a versatile and relatively simple way to enhance techniques for manipulating molecular trajectories.

The Journal of Physical Chemistry A•Jan 3, 2001•113 citations
The flow velocity of gas emerging from a supersonic nozzle mounted on a high-speed rotor can be largely canceled by the rotor velocity, thereby producing an intense beam of molecules traveling in a vacuum with translational speeds slowed to a few tens of meters per second. Centrifugal action significantly enhances the supersonic character of the gas flow from the rotating nozzle, further narrowing the spread of velocities in the emerging beam. These features are demonstrated by model calculations and experimental results for beams of Xe and for O 2 and CH 3 F seeded in Xe.
We describe a pulsed rotating supersonic beam source, evolved from an ancestral device [M. Gupta and D. Herschbach, J. Phys. Chem. A 105, 1626 (2001)]. The beam emerges from a nozzle near the tip of a hollow rotor which can be spun at high-speed to shift the molecular velocity distribution downward or upward over a wide range. Here we consider mostly the slowing mode. Introducing a pulsed gas inlet system, cryocooling, and a shutter gate eliminated the main handicap of the original device in which continuous gas flow imposed high background pressure. The new version provides intense pulses, of duration 0.1-0.6 ms (depending on rotor speed) and containing ∼10(12) molecules at lab speeds as low as 35 m/s and ∼10(15) molecules at 400 m∕s. Beams of any molecule available as a gas can be slowed (or speeded); e.g., we have produced slow and fast beams of rare gases, O(2), Cl(2), NO(2), NH(3), and SF(6). For collision experiments, the ability to scan the beam speed by merely adjusting the rotor is especially advantageous when using two merged beams. By closely matching the beam speeds, very low relative collision energies can be attained without making either beam very slow.
In this thesis I describe the second generation of a rotating supersonic beam source. The purpose of this device is to produce velocity augmented molecular beams for use with scattering experiments or subsequent slowing methods. The beam emerges from a nozzle inserted at the tip of a hollow aluminum rotor which can be spun at high speeds in either the forward or backwards direction. The forward direction mode increases the laboratory frame velocity distribution of the emitted beam and the backward direction mode decreases this velocity distribution.\n\nBoth rotor modes are analyzed theoretically and experimentally within the text. I introduce a pulsed gas inlet system for the rotating source as well as cryocooling of the vacuum chamber. This new version provides moderately intense beams of slow molecules, containing ∼1012 molecules at lab speeds as low as 35 m/s, and very intense beams of fast molecules, containing ∼1015 molecules at 400 m/s. Beams of any molecule available in gas phase can be produced utilizing this system. For collision experiments, the ability to scan the velocity utilizing the rotating source is very advantageous when using two merged beams. If the two velocities can be closely matched, very low relative collision energies can be produced without making either beam slow.
Intense beams of cold and slow molecules are produced by supersonic expansion out of a rapidly rotating nozzle, as first demonstrated by M. Gupta and D. Herschbach [J. Phys. Chem. A 103, 10670 (1999); 105, 1626 (2001)]. An improved setup is presented that is able to accelerate or decelerate cold atomic and molecular beams by up to 500 m/s. Technical improvements are discussed and beam parameters are characterized by detailed analysis of time-of-flight density distributions. The possibility of combining this beam source with electrostatic fields for guiding polar molecules is demonstrated.
We describe modifications of a pulsed rotating supersonic beam source that improve performance, particularly increasing the beam density and sharpening the pulse profiles. As well as providing the familiar virtues of a supersonic molecular beam (high intensity, narrowed velocity distribution, and drastic cooling of rotation and vibration), the rotating source enables scanning the translational velocity over a wide range. Thereby, beams of any atom or molecule available as a gas can be slowed or speeded. Using Xe beams in the slowing mode, we have obtained lab speeds down to about 40 ± 5 m/s with density near 10(11) cm(-3) and in the speeding mode lab speeds up to about 660 m/s and density near 10(14) cm(-3). We discuss some congenial applications. Providing low lab speeds can markedly enhance experiments using electric or magnetic fields to deflect, steer, or further slow polar or paramagnetic molecules. The capability to scan molecular speeds facilitates merging velocities with a codirectional partner beam, enabling study of collisions at very low relative kinetic energies, without requiring either beam to be slow.
Mounting a molecular beam source near the tip of a hollow high-speed rotor provides a means to shift the velocity distribution of the beam downward or upward over a wide range. We describe the construction of such a device and experiments and model calculations characterizing its operation, for both supersonic and effusive beams of rare gases, O 2, CH 3 F, and SF 6 . For example, the flow velocity of a rotating supersonic beam of O 2 was accelerated to above 1000 m/s (corresponding to a kinetic energy of 2200 K and deBroglie wavelength of 0.1 Å) and decelerated (when seeded in Xe) to below 70 m/s (corresponding to a kinetic energy below 10 K and deBroglie wavelength of nearly 2 Å). With improvements in prospect, the rotating beam source offers a versatile and relatively simple way to enhance techniques for manipulating molecular trajectories.