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

arXiv:0803.0650 · Physical Review A

Alternating-gradient focusing and deceleration of large molecules

Kirstin Wohlfart, Fabian Grätz, Frank Filsinger, Henrik Haak, Gerard Meijer, Jochen Küpper

Published Mar 24, 2008• 65 citations
arXivHTMLPDF

Abstract

We have focused and decelerated benzonitrile $({\mathrm{C}}_{7}{\mathrm{H}}_{5}\mathrm{N})$ molecules from a molecular beam, using an array of time-varying inhomogeneous electric fields in alternating-gradient configuration. Benzonitrile is prototypical for large asymmetric top molecules that exhibit rich rotational structure and a high density of states. At the rotational temperature of $3.5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in the pulsed molecular beam, many rotational states are populated. Benzonitrile molecules in their absolute ground state are decelerated from $320\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}289\phantom{\rule{0.3em}{0ex}}\mathrm{m}∕\mathrm{s}$, and similar changes in velocity are obtained for excited rotational states. All measurements agree well with the outcome of trajectory calculations. These experiments demonstrate that such large polyatomic molecules are amenable to the powerful method of Stark deceleration.

DOI
10.1103/physreva.77.031404

Related papers

Alternate Gradient Focusing and Deceleration of a Molecular Beam

Hendrick L. Bethlem, André J. A. van Roij, Rienk T. Jongma +1 more

Neutral dipolar molecules can be decelerated and trapped using time-varying inhomogeneous electric fields. This has been demonstrated only for molecules in low-field seeking states, but can, in principle, be performed on molecules in high-field seeking states as well. Transverse stability is then much more difficult to obtain, however, since molecules in high-field seeking states always experience a force towards the electrodes. Here we demonstrate that an array of dipole lenses in alternate gradient configuration can be used to maintain transverse stability. A pulsed beam of metastable CO in high-field seeking states is accelerated from 275 to 289 m/s as well as decelerated from 275 to 260 m/s.

Physical Review Letters•Mar 18, 2002•121 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

Slowing Heavy, Ground-State Molecules using an Alternating Gradient Decelerator

Michael R. Tarbutt, Hendrick L. Bethlem, J. J. Hudson +5 more

We have decelerated a supersonic beam of 174YbF molecules using a switched sequence of electrostatic field gradients. These molecules are 7 times heavier than any previously decelerated. An alternating gradient structure allows us to decelerate and focus the molecules in their ground state. We show that the decelerator exhibits the axial and transverse stability required to bring the molecules to rest. Our work significantly extends the range of molecules amenable to this powerful method of cooling and trapping.

arXiv:physics/0312119•Physical Review Letters•Apr 27, 2004•182 citations

Decelerating and Trapping Large Polar Molecules

David Patterson

Abstract Manipulating the motion of large polyatomic molecules, such as benzonitrile (C6H5CN), presents significant difficulties compared to the manipulation of diatomic molecules. Although recent impressive results have demonstrated manipulation, trapping, and cooling of molecules as large as CH3F, no general technique for trapping such molecules has been demonstrated, and cold neutral molecules larger than 5 atoms have not been trapped (M. Zeppenfeld, B. G. U. Englert, R. Glöckner, A. Prehn, M. Mielenz, C. Sommer, L. D. van Buuren, M. Motsch, G. Rempe, Nature 2012, 491, 570–573 ). In particular, extending Stark deceleration and electrostatic trapping to such species remains challenging. Here, we propose to combine a novel “asymmetric doublet state” Stark decelerator with recently demonstrated slow, cold, buffer‐gas‐cooled beams of closed‐shell volatile molecules to realize a general system for decelerating and trapping samples of a broad range of volatile neutral polar prolate asymmetric top molecules. The technique is applicable to most stable volatile molecules in the 100–500 AMU range, and would be capable of producing trapped samples in a single rotational state and at a motional temperature of hundreds of mK. Such samples would immediately allow for spectroscopy of unprecedented resolution, and extensions would allow for further cooling and direct observation of slow intramolecular processes such as vibrational relaxation and Hertz‐level tunneling dynamics.

ChemPhysChem•Jul 25, 2016•3 citations

Alternating-gradient focusing of the benzonitrile-argon van der Waals complex

Stephan Putzke, Frank Filsinger, Jochen Küpper +1 more

We report on the focusing and guiding of the van der Waals complex formed between benzonitrile molecules (C(6)H(5)CN) and argon atoms in a cold molecular beam using an ac electric quadrupole guide. The distribution of quantum states in the guided beam is non-thermal, because the transmission efficiency depends on the state-dependent effective dipole moment in the applied electric fields. At a specific ac frequency, however, the excitation spectrum can be described by a thermal distribution at a rotational temperature of 0.8 K. From the observed transmission characteristics and a combination of trajectory and Stark-energy calculations we conclude that the permanent electric dipole moment of benzonitrile remains unchanged upon the attachment of the argon atom to within ±5%. By exploiting the different dipole-moment-to-mass ([micro sign]/m) ratios of the complex and the benzonitrile monomer, transmission can be selectively suppressed for or, in the limit of 0 K rotational temperature, restricted to the complex.

arXiv:1208.3188•The Journal of Chemical Physics•Sep 12, 2012•7 citations

Stark deceleration of OH radicals in low-field-seeking and high-field-seeking quantum states

Kirstin Wohlfart, Frank Filsinger, Fabian Grätz +2 more

The Stark deceleration of OH radicals in both low-field-seeking and high-field-seeking levels of the rovibronic $^{2}\ensuremath{\Pi}_{3∕2}$, $v=0$, $J=3∕2$ ground state is demonstrated using a single experimental setup. Applying alternating-gradient focusing, OH radicals in their low-field-seeking $^{2}\ensuremath{\Pi}_{3∕2}$, $v=0$, $J=3∕2$, $f$ state have been decelerated from $345\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}239\phantom{\rule{0.3em}{0ex}}\mathrm{m}∕\mathrm{s}$, removing 50% of the kinetic energy using only 27 deceleration stages. The alternating-gradient decelerator allows one to independently control longitudinal and transverse manipulation of the molecules. Optimized high-voltage switching sequences for the alternating-gradient deceleration are applied, in order to adjust the dynamic focusing strength in every deceleration stage to the changing velocity over the deceleration process. In addition we have also decelerated OH radicals in their high-field-seeking $^{2}\ensuremath{\Pi}_{3∕2}$, $v=0$, $J=3∕2$, $e$ state from $355\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}316\phantom{\rule{0.3em}{0ex}}\mathrm{m}∕\mathrm{s}$. For the states involved, a real crossing of hyperfine levels occurs at $640\phantom{\rule{0.3em}{0ex}}\mathrm{V}∕\mathrm{cm}$, which is examined by varying a bias voltage applied to the electrodes.

arXiv:0807.4022•Physical Review A•Sep 18, 2008•34 citations
We have focused and decelerated benzonitrile (C7H5N)({\mathrm{C}}_{7}{\mathrm{H}}_{5}\mathrm{N})(C7​H5​N) molecules from a molecular beam, using an array of time-varying inhomogeneous electric fields in alternating-gradient configuration. Benzonitrile is prototypical for large asymmetric top molecules that exhibit rich rotational structure and a high density of states. At the rotational temperature of 3.5K3.5\phantom{\rule{0.3em}{0ex}}\mathrm{K}3.5K in the pulsed molecular beam, many rotational states are populated. Benzonitrile molecules in their absolute ground state are decelerated from 320to289m∕s320\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}289\phantom{\rule{0.3em}{0ex}}\mathrm{m}∕\mathrm{s}320to289m∕s, and similar changes in velocity are obtained for excited rotational states. All measurements agree well with the outcome of trajectory calculations. These experiments demonstrate that such large polyatomic molecules are amenable to the powerful method of Stark deceleration.
Neutral dipolar molecules can be decelerated and trapped using time-varying inhomogeneous electric fields. This has been demonstrated only for molecules in low-field seeking states, but can, in principle, be performed on molecules in high-field seeking states as well. Transverse stability is then much more difficult to obtain, however, since molecules in high-field seeking states always experience a force towards the electrodes. Here we demonstrate that an array of dipole lenses in alternate gradient configuration can be used to maintain transverse stability. A pulsed beam of metastable CO in high-field seeking states is accelerated from 275 to 289 m/s as well as decelerated from 275 to 260 m/s.
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.
We have decelerated a supersonic beam of 174YbF molecules using a switched sequence of electrostatic field gradients. These molecules are 7 times heavier than any previously decelerated. An alternating gradient structure allows us to decelerate and focus the molecules in their ground state. We show that the decelerator exhibits the axial and transverse stability required to bring the molecules to rest. Our work significantly extends the range of molecules amenable to this powerful method of cooling and trapping.
Abstract Manipulating the motion of large polyatomic molecules, such as benzonitrile (C6H5CN), presents significant difficulties compared to the manipulation of diatomic molecules. Although recent impressive results have demonstrated manipulation, trapping, and cooling of molecules as large as CH3F, no general technique for trapping such molecules has been demonstrated, and cold neutral molecules larger than 5 atoms have not been trapped (M. Zeppenfeld, B. G. U. Englert, R. Glöckner, A. Prehn, M. Mielenz, C. Sommer, L. D. van Buuren, M. Motsch, G. Rempe, Nature 2012, 491, 570–573 ). In particular, extending Stark deceleration and electrostatic trapping to such species remains challenging. Here, we propose to combine a novel “asymmetric doublet state” Stark decelerator with recently demonstrated slow, cold, buffer‐gas‐cooled beams of closed‐shell volatile molecules to realize a general system for decelerating and trapping samples of a broad range of volatile neutral polar prolate asymmetric top molecules. The technique is applicable to most stable volatile molecules in the 100–500 AMU range, and would be capable of producing trapped samples in a single rotational state and at a motional temperature of hundreds of mK. Such samples would immediately allow for spectroscopy of unprecedented resolution, and extensions would allow for further cooling and direct observation of slow intramolecular processes such as vibrational relaxation and Hertz‐level tunneling dynamics.
We report on the focusing and guiding of the van der Waals complex formed between benzonitrile molecules (C(6)H(5)CN) and argon atoms in a cold molecular beam using an ac electric quadrupole guide. The distribution of quantum states in the guided beam is non-thermal, because the transmission efficiency depends on the state-dependent effective dipole moment in the applied electric fields. At a specific ac frequency, however, the excitation spectrum can be described by a thermal distribution at a rotational temperature of 0.8 K. From the observed transmission characteristics and a combination of trajectory and Stark-energy calculations we conclude that the permanent electric dipole moment of benzonitrile remains unchanged upon the attachment of the argon atom to within ±5%. By exploiting the different dipole-moment-to-mass ([micro sign]/m) ratios of the complex and the benzonitrile monomer, transmission can be selectively suppressed for or, in the limit of 0 K rotational temperature, restricted to the complex.
The Stark deceleration of OH radicals in both low-field-seeking and high-field-seeking levels of the rovibronic $^{2}\ensuremath{\Pi}_{3∕2}$, v=0v=0v=0, J=3∕2J=3∕2J=3∕2 ground state is demonstrated using a single experimental setup. Applying alternating-gradient focusing, OH radicals in their low-field-seeking $^{2}\ensuremath{\Pi}_{3∕2}$, v=0v=0v=0, J=3∕2J=3∕2J=3∕2, fff state have been decelerated from 345to239m∕s345\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}239\phantom{\rule{0.3em}{0ex}}\mathrm{m}∕\mathrm{s}345to239m∕s, removing 50% of the kinetic energy using only 27 deceleration stages. The alternating-gradient decelerator allows one to independently control longitudinal and transverse manipulation of the molecules. Optimized high-voltage switching sequences for the alternating-gradient deceleration are applied, in order to adjust the dynamic focusing strength in every deceleration stage to the changing velocity over the deceleration process. In addition we have also decelerated OH radicals in their high-field-seeking $^{2}\ensuremath{\Pi}_{3∕2}$, v=0v=0v=0, J=3∕2J=3∕2J=3∕2, eee state from 355to316m∕s355\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}316\phantom{\rule{0.3em}{0ex}}\mathrm{m}∕\mathrm{s}355to316m∕s. For the states involved, a real crossing of hyperfine levels occurs at 640V∕cm640\phantom{\rule{0.3em}{0ex}}\mathrm{V}∕\mathrm{cm}640V∕cm, which is examined by varying a bias voltage applied to the electrodes.