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:1208.3188 · The Journal of Chemical Physics

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

Stephan Putzke, Frank Filsinger, Jochen Küpper, Gerard Meijer

Published Sep 12, 2012• 7 citations
arXivHTMLPDF

Abstract

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.

DOI
10.1063/1.4748814

Related papers

Rotational-state-specific guiding of large molecules

Stephan Putzke, Frank Filsinger, Henrik Haak +2 more

A beam of polar molecules can be focused and transported through an ac electric quadrupole guide. At a given ac frequency, the transmission of the guide depends on the mass-to-dipole-moment (m/μ) ratio of the molecular quantum state. Here we present a detailed characterization of the m/μ selector, using a pulsed beam of benzonitrile (C(6)H(5)CN) molecules in combination with rotational quantum state resolved detection. The arrival time distribution as well as the transverse velocity distribution of the molecules exiting the selector are measured as a function of ac frequency. The μ/Δμ resolution of the selector can be controlled by the applied ac waveforms and a value of up to 20 can be obtained with the present setup. This is sufficient to exclusively transmit benzonitrile molecules in quantum states with the same m/μ value as the absolute ground state. The operation characteristics of the m/μ selector are in quantitative agreement with the outcome of trajectory simulations.

arXiv:1103.5080•Physical Chemistry Chemical Physics•Jan 1, 2011•24 citations

Alternating-gradient focusing and deceleration of large molecules

Kirstin Wohlfart, Fabian Grätz, Frank Filsinger +3 more

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.

arXiv:0803.0650•Physical Review A•Mar 24, 2008•65 citations

Cold guided beams of polar molecules

M. Motsch

Slow molecules are efficiently extracted from a thermal reservoir by exploiting the interaction between polar molecules and the field provided by an electrostatic quadrupole guide. Electrostatic velocity filtering is widely applicable, which is demonstrated by producing guided beams of ammonia ND3, formaldehyde H2CO, and the water isotopologs H2O, D2O, and HDO. Ultraviolet depletion spectroscopy in a cold guided beam of formaldehyde makes the population in individual rotational states visible and testifies their key role in velocity filtering. Enhanced Rayleigh scattering into an optical cavity is investigated as an alternative non-destructive detection method for cold molecules. For various room-temperature gases, the observed enhancement is well described by interference of electromagnetic fields scattered into the resonator by a classical driven dipole oscillator.

•Jan 1, 2010•1 citation

Manipulation of the motion of polyatomic molecules in the rotational ground state : microwave lens effect by AC Stark dipole force

Zhong, Wei

The main contribution of this project to the field of cold and ultracold molecules is we firstly demonstrated successful manipulation of the motion of polyatomic molecular beam in the rotational ground state, which has the lowest temperature of all possible states. Chapter 1 gives a summary of this field, including the application of cold and ultracold molecules, the methods to obtain them, and each method’s advantages and disadvantages. Once we decelerate molecular ensembles, we would like to trap the cold and ultracold molecules in electric trap, megnetic trap and megneto-optical trap. Chapter 2 starts with an introduction of the concept of supersonic beam and the basic knowledge of it, such as the specific features. The experimental setup will also be presented and explained in this chapter. The main highlight of this project is that we are manipulating molecules in the real ground state. Our molecular source is a Counter Rotating Nozzle(CRN), which can precool (or slow in alternate terminology) molecules in all states including the rotational ground state. The principle and performance of CRN will be presented and explained in Chapter 3. After obtaining a well precooled molecular beam, the microwave lens effect on various species is presented in Chapter 4. Meanwhile, the principle of AC Stark shift, AC dipole force and the microwave standing wave modes, such as TE modes and TM modes, will be explained in this chapter as well. Finally, I’ll summarize, draw conclusion of this work and describe the future expectation of this project in Chapter 5.

•Jan 1, 2013•0 citations

State-selective detection of velocity-filtered ND 3 molecules

Benjamin Bertsche, Andreas Osterwalder

Translationally cold and slow ND${}_{3}$ is prepared by filtering the slow molecules from a thermal gas-phase sample using a curved electrostatic hexapole guide. This filter, like the curved quadrupole guide introduced by Rangwala et al. [Phys. Rev. A 67, 043406 (2003)] selects molecules by their forward velocity and effective electric dipole moment. Here we describe two main modifications with respect to previous work: (1) A segmented hexapole guide is used that produces a harmonic potential for the linearly Stark-shifted levels of ND${}_{3}$. A curved guide is combined with a straight hexapole guide, and independent high-voltage supplies are employed to allow for bandpass velocity filtering. (2) State-selective laser ionization is used to obtain time- and state-selective detection of the guided molecules. This enables the experimental determination of the rotational state population of the guided molecules.

arXiv:1004.3812•Physical Review A•Sep 17, 2010•29 citations

Hexapole State-Selection and Beam Focus of Linear Triatomic Molecules

Fuchun Liu, Jin Ming-Xing, Dajun Ding

The state selection and beam focus of linear triatomic molecules (OCS, HCN, ClCN, BrCN and ICN) with doubling states in a hexapole electric field have been numerically realized. The method is based on a quantum mechanical treatment of the molecular Stark energy and a classical mechanical treatment for the molecular trajectory in the field. In linear molecules with doubling states, the second-order Stark effect can be neglected and the doubling states have the same value of J and M . The influences of the molecular properties, state energies, and the apparatus parameters such as molecular beam temperature and length of the hexapole, on the role of state selection and focus have been discussed. The method established here can be taken as a guide for hexapole experiment of orientation of polar molecules.

Chinese Physics Letters•Apr 28, 2006•8 citations
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.
A beam of polar molecules can be focused and transported through an ac electric quadrupole guide. At a given ac frequency, the transmission of the guide depends on the mass-to-dipole-moment (m/μ) ratio of the molecular quantum state. Here we present a detailed characterization of the m/μ selector, using a pulsed beam of benzonitrile (C(6)H(5)CN) molecules in combination with rotational quantum state resolved detection. The arrival time distribution as well as the transverse velocity distribution of the molecules exiting the selector are measured as a function of ac frequency. The μ/Δμ resolution of the selector can be controlled by the applied ac waveforms and a value of up to 20 can be obtained with the present setup. This is sufficient to exclusively transmit benzonitrile molecules in quantum states with the same m/μ value as the absolute ground state. The operation characteristics of the m/μ selector are in quantitative agreement with the outcome of trajectory simulations.
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.
Slow molecules are efficiently extracted from a thermal reservoir by exploiting the interaction between polar molecules and the field provided by an electrostatic quadrupole guide. Electrostatic velocity filtering is widely applicable, which is demonstrated by producing guided beams of ammonia ND3, formaldehyde H2CO, and the water isotopologs H2O, D2O, and HDO. Ultraviolet depletion spectroscopy in a cold guided beam of formaldehyde makes the population in individual rotational states visible and testifies their key role in velocity filtering. Enhanced Rayleigh scattering into an optical cavity is investigated as an alternative non-destructive detection method for cold molecules. For various room-temperature gases, the observed enhancement is well described by interference of electromagnetic fields scattered into the resonator by a classical driven dipole oscillator.
The main contribution of this project to the field of cold and ultracold molecules is we firstly demonstrated successful manipulation of the motion of polyatomic molecular beam in the rotational ground state, which has the lowest temperature of all possible states. Chapter 1 gives a summary of this field, including the application of cold and ultracold molecules, the methods to obtain them, and each method’s advantages and disadvantages. Once we decelerate molecular ensembles, we would like to trap the cold and ultracold molecules in electric trap, megnetic trap and megneto-optical trap. Chapter 2 starts with an introduction of the concept of supersonic beam and the basic knowledge of it, such as the specific features. The experimental setup will also be presented and explained in this chapter. The main highlight of this project is that we are manipulating molecules in the real ground state. Our molecular source is a Counter Rotating Nozzle(CRN), which can precool (or slow in alternate terminology) molecules in all states including the rotational ground state. The principle and performance of CRN will be presented and explained in Chapter 3. After obtaining a well precooled molecular beam, the microwave lens effect on various species is presented in Chapter 4. Meanwhile, the principle of AC Stark shift, AC dipole force and the microwave standing wave modes, such as TE modes and TM modes, will be explained in this chapter as well. Finally, I’ll summarize, draw conclusion of this work and describe the future expectation of this project in Chapter 5.
Translationally cold and slow ND3{}_{3}3​ is prepared by filtering the slow molecules from a thermal gas-phase sample using a curved electrostatic hexapole guide. This filter, like the curved quadrupole guide introduced by Rangwala et al. [Phys. Rev. A 67, 043406 (2003)] selects molecules by their forward velocity and effective electric dipole moment. Here we describe two main modifications with respect to previous work: (1) A segmented hexapole guide is used that produces a harmonic potential for the linearly Stark-shifted levels of ND3{}_{3}3​. A curved guide is combined with a straight hexapole guide, and independent high-voltage supplies are employed to allow for bandpass velocity filtering. (2) State-selective laser ionization is used to obtain time- and state-selective detection of the guided molecules. This enables the experimental determination of the rotational state population of the guided molecules.
The state selection and beam focus of linear triatomic molecules (OCS, HCN, ClCN, BrCN and ICN) with doubling states in a hexapole electric field have been numerically realized. The method is based on a quantum mechanical treatment of the molecular Stark energy and a classical mechanical treatment for the molecular trajectory in the field. In linear molecules with doubling states, the second-order Stark effect can be neglected and the doubling states have the same value of J and M . The influences of the molecular properties, state energies, and the apparatus parameters such as molecular beam temperature and length of the hexapole, on the role of state selection and focus have been discussed. The method established here can be taken as a guide for hexapole experiment of orientation of polar molecules.