Manipulation and Control of Molecular Beams

Meerakker, Sebastiaan Y. T. van de; Bethlem, Hendrick L.; Vanhaecke, Nicolas; Meijer, Gerard

doi:10.1021/cr200349r

Cited by 316 publications

(387 citation statements)

References 288 publications

Supporting

Mentioning

376

Contrasting

Unclassified

Order By: Relevance

“…This method has been described previously in Ref. [25]. Recently, a new method of Stark deceleration has been demonstrated in which a series of ring electrodes, with continuously varying voltages applied, create a true moving potential well that decelerates molecules [26].…”

Section: Stark Deceleration Of a Position/velocity Correlated Beammentioning

confidence: 99%

Method for traveling-wave deceleration of buffer-gas beams of CH

et al. 2014

View full text Add to dashboard Cite

Cryogenic buffer-gas beams are a promising method for producing bright sources of cold molecular radicals for cold collision and chemical reaction experiments. In order to use these beams in studies of reactions with controlled collision energies, or in trapping experiments, one needs a method of controlling the forward velocity of the beam. A Stark decelerator can be an effective tool for controlling the mean speed of molecules produced by supersonic jets, but efficient deceleration of buffer-gas beams presents new challenges due to longer pulse lengths. Traveling-wave decelerators are uniquely suited to meet these challenges because of their ability to confine molecules in three dimensions during deceleration and their versatility afforded by the analog control of the electrodes. We have created ground state CH(X 2 Π) radicals in a cryogenic buffer-gas cell with the potential to produce a cold molecular beam of 10 11 mol./pulse. We present a general protocol for Stark deceleration of beams with a large position and velocity spread for use with a traveling-wave decelerator. Our method involves confining molecules transversely with a hexapole for an optimized distance before deceleration. This rotates the phase-space distribution of the molecular packet so that the packet is matched to the time varying phase-space acceptance of the decelerator. We demonstrate with simulations that this method can decelerate a significant fraction of the molecules in successive wells of a traveling-wave decelerator to produce energy-tuned beams for cold and controlled molecule experiments.

show abstract

Section: Stark Deceleration Of a Position/velocity Correlated Beammentioning

confidence: 99%

Method for traveling-wave deceleration of buffer-gas beams of CH

et al. 2014

View full text Add to dashboard Cite

show abstract

“…In particular, Stark and Zeeman decelerators have been developed to control the motion of molecules that possess an electric and magnetic dipole moment using time-varying electric and magnetic fields, respectively. Since the first experimental demonstration of Stark deceleration in 1998 [1], several decelerators ranging in size and complexity have been constructed [2][3][4]. Applications of these controlled molecular beams are found in high-resolution spectroscopy, the trapping of molecules at low temperature, and advanced scattering experiments that exploit the unprecedented state-purity and/or velocity control of the packets of molecules emerging from the decelerator [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Multistage Zeeman decelerator for molecular-scattering studies

Cremers¹,

Chefdeville²,

Janssen³

et al. 2017

Phys. Rev. A

Self Cite

View full text Add to dashboard Cite

We present a concept for a multistage Zeeman decelerator that is optimized particularly for applications in molecular beam scattering experiments. The decelerator consists of a series of alternating hexapoles and solenoids, that effectively decouple the transverse focusing and longitudinal deceleration properties of the decelerator. It can be operated in a deceleration and acceleration mode, as well as in a hybrid mode that makes it possible to guide a particle beam through the decelerator at constant speed. The deceleration features phase stability, with a relatively large six-dimensional phase-space acceptance. The separated focusing and deceleration elements result in an unequal partitioning of this acceptance between the longitudinal and transverse directions. This is ideal in scattering experiments, which typically benefit from a large longitudinal acceptance combined with narrow transverse distributions. We demonstrate the successful experimental implementation of this concept using a Zeeman decelerator consisting of an array of 25 hexapoles and 24 solenoids. The performance of the decelerator in acceleration, deceleration, and guiding modes is characterized using beams of metastable helium ( 3 S) atoms. Up to 60% of the kinetic energy was removed for He atoms that have an initial velocity of 520 m/s. The hexapoles consist of permanent magnets, whereas the solenoids are produced from a single hollow copper capillary through which cooling liquid is passed. The solenoid design allows for excellent thermal properties and enables the use of readily available and cheap electronics components to pulse high currents through the solenoids. The Zeeman decelerator demonstrated here is mechanically easy to build, can be operated with cost-effective electronics, and can run at repetition rates up to 10 Hz.

show abstract

“…Over the last decade, the manipulation of the motion of molecules using electric fields has been revitalized [1][2][3][4][5]. Exploiting the Stark effect, large asymmetric-top polar molecules have been deflected [6], focused [7], and decelerated [8].…”

Section: Introductionmentioning

confidence: 99%

CMIstark: Python package for the Stark-effect calculation and symmetry classification of linear, symmetric and asymmetric top wavefunctions in dc electric fields

Chang

Filsinger

Sartakov

et al. 2014

Computer Physics Communications

View full text Add to dashboard Cite

a b s t r a c tThe Controlled Molecule Imaging group (CMI) at the Center for Free Electron Laser Science (CFEL) has developed the CMIstark software to calculate, view, and analyze the energy levels of adiabatic Stark energy curves of linear, symmetric top and asymmetric top molecules. The program exploits the symmetry of the Hamiltonian to generate fully labeled adiabatic Stark energy curves.CMIstark is written in Python and easily extendable, while the core numerical calculations make use of machine optimized BLAS and LAPACK routines. Calculated energies are stored in HDF5 files for convenient access and programs to extract ASCII data or to generate graphical plots are provided. Chang et al. / Computer Physics Communications 185 (2014) [339][340][341][342][343][344][345][346][347][348][349] Nature of problem: Calculation of the Stark effect of asymmetric top molecules in arbitrarily strong dc electric fields in a correct symmetry classification and using correct labeling of the adiabatic Stark curves. Program summary Solution method:We set up the full M matrices of the quantum-mechanical Hamiltonian in the basis set of symmetric top wavefunctions and, subsequently, Wang transform the Hamiltonian matrix. We separate, as far as possible, the sub-matrices according to the remaining symmetry, and then diagonalize the individual blocks. This application of the symmetry consideration to the Hamiltonian allows an adiabatic correlation of the asymmetric top eigenstates in the dc electric field to the field-free eigenstates. This directly yields correct adiabatic state labels and, correspondingly, adiabatic Stark energy curves. Restrictions:The maximum value of J is limited by the available main memory. A modern desktop computer with 16 GB of main memory allows for calculations including all Js up to a values larger than 100 even for the most complex cases of asymmetric tops. Running time:Typically 1 s-1 week on a single CPU or equivalent on multi-CPU systems (depending greatly on system size and RAM); parallelization through BLAS/LAPACK. For instance, calculating all energies up to J = 25 of indole (vide infra) for one field strength takes 1 CPU-s on a current iMac.

show abstract

Manipulation and Control of Molecular Beams

Cited by 316 publications

References 288 publications

Method for traveling-wave deceleration of buffer-gas beams of CH

Method for traveling-wave deceleration of buffer-gas beams of CH

Multistage Zeeman decelerator for molecular-scattering studies

CMIstark: Python package for the Stark-effect calculation and symmetry classification of linear, symmetric and asymmetric top wavefunctions in dc electric fields

Contact Info

Product

Resources

About