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

Conference on Lasers and Electro-Optics

Towards ultracold chemistry; manipulation of polar molecules with electric fields

Jochen Küpper, Hendrick L. Bethlem, Floris M. H. Crompvoets, Sebastiaan Y. T. van de Meerakker, Nicolas Vanhaecke, Jacqueline van Veldhoven, Kirstin Wohlfart, Gerard Meijer

Published Jan 1, 2005• 0 citations
Publisher

Abstract

Deceleration and trapping of polar molecules using time-varying electric fields is described. Decelerated ND3 and OH molecules are trapped in an electrostatic trap, slow beams of ammonia are injected in a storage ring and have also been used for testing micro-structured optical elements and for high-resolution spectroscopy. Alternate gradient deceleration and AC electric trapping of ground-state molecules is discussed.

DOI
10.1109/iqec.2005.1560872

Related papers

Deceleration and trapping of polar molecules using time-varying electric fields

Hendrick L. Bethlem

What we experience as an agreeable temperature is in fact due to a constant bombardment of our skin by very fast molecules. At room temperature the average velocity of air molecules around us is about 500 m/s, corresponding to about 2000 km/hour. Only at very low temperatures, close to the absolute zero (0 K = -273.15 C), will the molecules come to rest. The high velocities at ordinary temperatures limit our ability to study the molecules. This thesis describes a method to slow down a beam of polar molecules using time-varying electric fields. When the molecules are decelerated to low velocities they will have insufficient kinetic energy to escape from the electric fields, and they will be trapped. In this way molecules can be stored and studied over long periods of time. This thesis is organized as follows: In chapter I the motivation for studying cold molecules is made more explicit, and an overview is given of other methods to cool molecules. In Chapter II the interaction between molecules and electric fields is outlined. In Chapter III and IV deceleration of a beam of metastable CO is presented, using molecules in states which are either repelled by, or attracted to high electric fields. Finally, in Chapter V ammonia molecules are brought to a standstill and subsequently held in an electrostatic trap

APS•Jan 1, 2002•3 citations

Deceleration and trapping of ammonia using time-varying electric fields

Hendrick L. Bethlem, Floris M. H. Crompvoets, Rienk T. Jongma +2 more

A polar molecule experiences a force in an inhomogeneous electric field. Using this force, neutral molecules can be decelerated and trapped. It is shown here that this can in principle be done without loss in phase-space density. Using a series of 64 pulsed inhomogeneous electric fields a supersonic beam of ammonia molecules ${(}^{14}{\mathrm{NH}}_{3},$ ${}^{14}{\mathrm{ND}}_{3},$ ${}^{15}{\mathrm{ND}}_{3})$ is decelerated. Subsequently, the decelerated molecules are loaded into an electrostatic quadrupole trap. Densities on the order of ${10}^{7} {\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{e}\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{e}\mathrm{s}/\mathrm{c}\mathrm{m}}^{3}$ at a temperature of 25 mK are obtained for ${}^{14}{\mathrm{ND}}_{3}$ and ${}^{15}{\mathrm{ND}}_{3}$ separately and simultaneously. This corresponds to a phase-space density in the trap of $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13},$ 50 times less than the initial phase-space density in the beam.

Physical Review A•May 10, 2002•231 citations

STARK DECELERATION AND TRAPPING OF OH RADICALS

Sebastiaan Y. T. van de Meerakker, Nicolas Vanhaecke, Gerard Meijer

The motion of polar molecules can be controlled by time-varying inhomogeneous electric fields. In a Stark decelerator, this is exploited to accelerate, transport, or decelerate a fraction of a molecular beam. When combined with a trap, the decelerator provides a means to store the molecules for times up to seconds. Here, we review our efforts to produce cold molecules via this technique. In particular, we present a new generation Stark decelerator and electrostatic trap that selects a significant part of a molecular beam pulse that can be loaded into the trap. Deceleration and trapping experiments using a beam of OH radicals are discussed.

Annual Review of Physical Chemistry•Dec 1, 2005•90 citations

Production and application of translationally cold molecules

Hendrick L. Bethlem, Gerard Meijer

Inspired by the spectacular successes in the field of cold atoms, there is currently great interest in cold molecules. Cooling molecules is useful for various fundamental physics studies and gives access to an exotic regime in chemistry where the wave property of the molecules becomes important. Although cooling molecules has turned out to be considerably more difficult than cooling atoms, a number of methods to produce samples of cold molecules have been demonstrated over the last few years. This paper aims to review the application of cold molecules and the methods to produce them. Emphasis is put on the deceleration of polar molecules using time-varying electric fields. The operation principle of the array of electrodes that is used to decelerate polar molecules is described in analogy with, and using terminology from, charged-particle accelerators. It is shown that, by applying an appropriately timed high voltage burst, molecules can be decelerated while the phase-space density, i.e. the number of molecules per position-velocity interval, remains constant. In this way the high density and low temperature in the moving frame of a pulsed molecular beam can be transferred to the laboratory frame. Experiments on metastable CO in states that are either repelled by or attracted to high electric fields are presented. Loading of slow molecules into traps and storage rings is discussed.

International Reviews in Physical Chemistry•Jan 1, 2003•229 citations

Manipulating Polar Molecules: Traps, Synchrotrons and Chips

Gerard Meijer

The motion of polar molecules in a beam can be manipulated with electric fields. Decelerated beams of molecules can be loaded in traps or storage rings, and manipulation of molecules on a chip is demonstrated.

Frontiers in Optics•Jan 1, 2008•0 citations

Alternating gradient focusing and deceleration of polar molecules

Hendrick L. Bethlem, Michael R. Tarbutt, Jochen Küpper +4 more

Beams of polar molecules can be focused using an array of electrostatic lenses in alternating gradient (AG) configuration. They can also be accelerated or decelerated by applying an appropriate high-voltage switching sequence to the lenses. AG focusing is applicable to molecules in both low-field- and high-field-seeking states and is particularly well suited to the problem of decelerating heavy molecules and those in their ground rotational state. We describe the principles of AG deceleration and set out criteria to be followed in decelerator design, construction and operation. We calculate the longitudinal and transverse focusing properties of a decelerator, and exemplify this by 2D-imaging studies of a decelerated beam of metastable CO molecules.

arXiv:physics/0604020•Journal of Physics B Atomic Molecular and Optical Physics•Aug 8, 2006•86 citations
Deceleration and trapping of polar molecules using time-varying electric fields is described. Decelerated ND3 and OH molecules are trapped in an electrostatic trap, slow beams of ammonia are injected in a storage ring and have also been used for testing micro-structured optical elements and for high-resolution spectroscopy. Alternate gradient deceleration and AC electric trapping of ground-state molecules is discussed.
What we experience as an agreeable temperature is in fact due to a constant bombardment of our skin by very fast molecules. At room temperature the average velocity of air molecules around us is about 500 m/s, corresponding to about 2000 km/hour. Only at very low temperatures, close to the absolute zero (0 K = -273.15 C), will the molecules come to rest. The high velocities at ordinary temperatures limit our ability to study the molecules. This thesis describes a method to slow down a beam of polar molecules using time-varying electric fields. When the molecules are decelerated to low velocities they will have insufficient kinetic energy to escape from the electric fields, and they will be trapped. In this way molecules can be stored and studied over long periods of time. This thesis is organized as follows: In chapter I the motivation for studying cold molecules is made more explicit, and an overview is given of other methods to cool molecules. In Chapter II the interaction between molecules and electric fields is outlined. In Chapter III and IV deceleration of a beam of metastable CO is presented, using molecules in states which are either repelled by, or attracted to high electric fields. Finally, in Chapter V ammonia molecules are brought to a standstill and subsequently held in an electrostatic trap
A polar molecule experiences a force in an inhomogeneous electric field. Using this force, neutral molecules can be decelerated and trapped. It is shown here that this can in principle be done without loss in phase-space density. Using a series of 64 pulsed inhomogeneous electric fields a supersonic beam of ammonia molecules (14NH3,{(}^{14}{\mathrm{NH}}_{3},(14NH3​, 14ND3,{}^{14}{\mathrm{ND}}_{3},14ND3​, 15ND3){}^{15}{\mathrm{ND}}_{3})15ND3​) is decelerated. Subsequently, the decelerated molecules are loaded into an electrostatic quadrupole trap. Densities on the order of 107molecules/cm3{10}^{7} {\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{e}\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{e}\mathrm{s}/\mathrm{c}\mathrm{m}}^{3}107molecules/cm3 at a temperature of 25 mK are obtained for 14ND3{}^{14}{\mathrm{ND}}_{3}14ND3​ and 15ND3{}^{15}{\mathrm{ND}}_{3}15ND3​ separately and simultaneously. This corresponds to a phase-space density in the trap of $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13},$ 50 times less than the initial phase-space density in the beam.
The motion of polar molecules can be controlled by time-varying inhomogeneous electric fields. In a Stark decelerator, this is exploited to accelerate, transport, or decelerate a fraction of a molecular beam. When combined with a trap, the decelerator provides a means to store the molecules for times up to seconds. Here, we review our efforts to produce cold molecules via this technique. In particular, we present a new generation Stark decelerator and electrostatic trap that selects a significant part of a molecular beam pulse that can be loaded into the trap. Deceleration and trapping experiments using a beam of OH radicals are discussed.
Inspired by the spectacular successes in the field of cold atoms, there is currently great interest in cold molecules. Cooling molecules is useful for various fundamental physics studies and gives access to an exotic regime in chemistry where the wave property of the molecules becomes important. Although cooling molecules has turned out to be considerably more difficult than cooling atoms, a number of methods to produce samples of cold molecules have been demonstrated over the last few years. This paper aims to review the application of cold molecules and the methods to produce them. Emphasis is put on the deceleration of polar molecules using time-varying electric fields. The operation principle of the array of electrodes that is used to decelerate polar molecules is described in analogy with, and using terminology from, charged-particle accelerators. It is shown that, by applying an appropriately timed high voltage burst, molecules can be decelerated while the phase-space density, i.e. the number of molecules per position-velocity interval, remains constant. In this way the high density and low temperature in the moving frame of a pulsed molecular beam can be transferred to the laboratory frame. Experiments on metastable CO in states that are either repelled by or attracted to high electric fields are presented. Loading of slow molecules into traps and storage rings is discussed.
Beams of polar molecules can be focused using an array of electrostatic lenses in alternating gradient (AG) configuration. They can also be accelerated or decelerated by applying an appropriate high-voltage switching sequence to the lenses. AG focusing is applicable to molecules in both low-field- and high-field-seeking states and is particularly well suited to the problem of decelerating heavy molecules and those in their ground rotational state. We describe the principles of AG deceleration and set out criteria to be followed in decelerator design, construction and operation. We calculate the longitudinal and transverse focusing properties of a decelerator, and exemplify this by 2D-imaging studies of a decelerated beam of metastable CO molecules.