Manipulating the motion of large neutral molecules

Küpper, Jochen; Filsinger, Frank; Meijer, Gerard

doi:10.1039/b820045a

Cited by 28 publications

(36 citation statements)

References 81 publications

(123 reference statements)

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“…23 These techniques are extendable to larger polar molecules such as benzonitrile (C 6 H 5 CN, 4.2 Debye) or azulene, a polar isomer of naphthalene (C 10 H 8 , 0.8 Debye). 24 Such a beam of larger polar molecules would make an attractive source for alternating gradient decelerators such as those demonstrated by Meijer et al 4 This cooling method is also promising as a tool for investigating cold chemistry. There has been much recent interest in cold gas-phase chemical reactions, including interest in chemistry in the interstellar medium, 25 spin and orientation mediated chemical reactions, 26 and field mediated reactions.…”

Section: Cold Beam Productionmentioning

confidence: 99%

“…The cold molecules in these studies are generally diatomic but also include few-atom molecules such as ND 3 . 2,3 Extending this work to the cooling of larger molecules is of high interest, as reviewed by Meijer et al 4 and references therein. For example, chemical reaction rates at low temperatures are of great current interest, and extending these studies to important large molecules is essential.…”

Section: Introductionmentioning

confidence: 95%

“…However, the only demonstrated technique for producing samples of neutral cold molecules with atom number higher than five is the seeded supersonic jet. Seeded supersonic beams have a rich history and have found great utility in spectroscopic studies, 7 as sources for molecular trapping experiments, 4 and in cold chemistry experiments using the CRESU technique. 8 They are limited, however, because although they produce translationally and rotationally cold molecules, these molecules are moving at very high velocity (300 m s À1 or higher).…”

Section: Introductionmentioning

confidence: 99%

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Cooling and collisions of large gas phase molecules

Patterson

Tsikata

Doyle

2010

Phys. Chem. Chem. Phys.

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The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters. Cold and dense samples of naphthalene (C 10 H 8 ) are produced using buffer gas cooling in combination with rapid, high flow molecule injection. The observed naphthalene density is n E 10 11 cm À3 over a volume of a few cm 3 at a temperature of 6 K. We observe naphthalene-naphthalene collisions through two-body loss of naphthalene with a loss cross section of s N-N = 1.4 Â 10 À14 cm 2 . Analysis is presented that indicates that this combination of techniques will be applicable to many comparably sized molecules. This technique can also be combined with cryogenic beam methods 1 to produce cold, high flux, continuous molecular beams.

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Section: Cold Beam Productionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Cooling and collisions of large gas phase molecules

Patterson

Tsikata

Doyle

2010

Phys. Chem. Chem. Phys.

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“…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

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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.

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“…In Figure 10 the calculated energies for a few of the lowest rotational states of benzonitrile (C 7 H 5 N) are shown. These curves are obtained by setting up the Hamiltonian matrix based on the known matrix elements 149 and spectroscopically obtained rotational constants and dipole moments. 148 From Figure 10 it is obvious that for all quantum states of benzonitrile the energy decreases with increasing field strength for practically relevant electric fields (50-200 kV/cm) and these states are called "highfield seeking".…”

Section: A3 Manipulation Of Polar Molecules Via the Stark Effectmentioning

confidence: 99%

Manipulating the Motion of Complex Molecules: Deflection, Focusing, and Deceleration of Molecular Beams for Quantum‐State and Conformer Selection

Küpper

Filsinger

Meijer

et al. 2012

Methods in Physical Chemistry

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Method summary Acronyms• effective dipole moment (µ eff )• low-field seeking (lfs) state• high-field seeking (hfs) state • Alternating gradient (AG) focusing• photo-multiplier tube (PMT)• transition state (TS) Strengths of technique• allows to spatially separate molecules in different quantum states, including isomers of complex molecules• versatile -DC field techniques can be applied to all polar molecules, AC field techniques to all polarizable molecules (= all molecules)• quantum-state specific interaction -can, in principle, be used to separate all kinds of isomers• determination of rotational, vibrational, and electronic properties -including dipole moments and polarizabilities -of single isomers of complex molecules• allows for detailed investigations of stereochemical dynamics• allows to separate molecular ensembles from seedgas, avoiding background in various scattering experiments Limitations• translations of non-polar molecules can -for practical purposes -not be manipulated by dc electric fields• no ultracold samples (µK or below) produced so far * This chapter is largely based on parts of reference 1. † Email: jochen.kuepper@cfel.de 1 2 Controlled moleculesChemists have long been dreaming of ultimately controlling all aspects of chemical reactions. Empirically, vast progress has been made over the last centuries using increasingly sophisticated techniques to dictate the path and outcome of chemical reactions. However, in all these approaches external parameters are used to (classically) shift statistical outcomes one way or another. Recently, the field of cold and ultracold chemistry has started to provide a glimpse at a new level of control, where full quantum-mechanical control can be obtained. So far this has been demonstrated for very specific small reactions systems, i. e., for reactions of alkali dimers with alkali atoms 2,3 or with each other, including the observation of stereochemical effects. 4 In these experiments molecules are prepared at low temperatures and specific quantum states starting from ultracold ensembles oftypically alkali -atoms, which is the limiting factor to the possible complexity and versatility of these methods. Alternatively, cold collisions of small molecules, i. e., OH radicals, with rare gas atoms at arbitrarily low collision energies have been investigated. 5,6 In this chapter we will present the available methods to gain control over the motion and the quantum-state populations over complex molecules (albeit at a lower level). These methods could enable a new level of detail in the study and control of chemical reactions for a large variety of molecules. Moreover, the prepared samples of controlled molecules are useful in a wide variety of experiments, ranging from the taking of actual photographs of the molecules -and their inherent or induced dynamics -using ultrafast X-ray or electron diffraction over, for example, photoelectron distributions and high-harmonic generation to investigations of attosecond electron dynamics and charge migration. 7 These experiments...

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Manipulating the motion of large neutral molecules

Cited by 28 publications

References 81 publications

Cooling and collisions of large gas phase molecules

Cooling and collisions of large gas phase molecules

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

Manipulating the Motion of Complex Molecules: Deflection, Focusing, and Deceleration of Molecular Beams for Quantum‐State and Conformer Selection

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