Hexapole state selection and focusing vs. brute force orientation of beam molecules

The induced polarization of a beam of polar clusters or molecules passing through an electric or magnetic field region differs from the textbook Langevin-Debye susceptibility. This distinction, which is important for the interpretation of deflection and focusing experiments, arises because instead of acquiring thermal equilibrium in the field region, the beam ensemble typically enters the field adiabatically, i.e., with a previously fixed distribution of rotational states. We discuss the orientation of rigid symmetric top systems with a body-fixed electric or magnetic dipole moment. The analytical expression for their "adiabatic-entry" orientation is elucidated and compared with exact numerical results for a range of parameters. The differences between the polarization of thermodynamic and "adiabatic-entry" ensembles of prolate and oblate tops, and of symmetric top and linear rotators, are illustrated and identified.

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“…The procedure of computing the average orientation from the eigenvectors is described is described in Ref. 29.…”

Section: Comparison With Exact Evaluationmentioning

confidence: 99%

Orientation of dipole molecules and clusters upon adiabatic entry into an external field

Bulthuis

Becker

Moro

et al. 2008

The Journal of Chemical Physics

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“…In the case where orientation after focusing may be difficult, 52,53 "brute force" may be required. [54][55][56][57] The enantiomeric selected forms can be used for investigations of chirality effects.…”

Section: Discussionmentioning

confidence: 99%

Electrostatic Hexapole State-Selection of the Asymmetric-Top Molecule Propylene Oxide

et al. 2010

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Rotational state-selection of the asymmetric-top molecule propylene oxide was carried out using an electrostatic hexapole field of 85-cm length. Molecular beam intensities were monitored by a quadrupole mass spectrometer. It was found that beam intensities of molecular beams for pure propylene oxide and those seeded in He and in Ar increased with increasing hexapole voltages. The hexapole voltage dependence of the beam intensity, which is called the focusing curve, was interpreted by computer simulation of the trajectories of molecules in the hexapolar field due to the Stark effect, as a function of rotational temperatures of molecular beams. The calculated best fit focusing curves, when compared with the experimental results, demonstrated that the rotational temperatures, associated with the distribution of states of a given rotational angular momentum J, are similar to the translational temperatures. It was found that the M = 0 states (where M is the projection of J along the direction of the electrostatic field) and negative values of the pseudoquantum number tau of propylene oxide can be selected using our experimental setup. These results suggest that the hexapole electric field is a tool even for the selection of rotational and orientation states of asymmetric-top molecules.

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“…For example, the use of hexapole devices as well as so-called "brute-force" methods to select oriented neutral molecules has been employed in "stereodynamic" studies of bimolecular reactions. [41][42][43][44] This is effectively a form of control applied to the rotational degree of freedom, as will be expanded upon later. Other types of approach have also been used to exert control over the translational degree of freedom of neutral atoms and molecules via electrostatic interactions.…”

Section: Controlmentioning

confidence: 99%

A Stark Future for Quantum Control

2010

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We present an overview of developments using the nonresonant dynamic Stark effect within the fields of time-resolved molecular dynamics and quantum control, drawing on examples from our own recent work. Particular emphasis is placed on the notion that "dynamics" and "control" are not distinct disciplines and that a clear synergy exits between these areas which has, up to now, been somewhat underexploited. The dynamic Stark effect is a universal interaction which we expect to have broad applicability.

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Hexapole state selection and focusing vs. brute force orientation of beam molecules

Cited by 60 publications

References 27 publications

Orientation of dipole molecules and clusters upon adiabatic entry into an external field

Orientation of dipole molecules and clusters upon adiabatic entry into an external field

Electrostatic Hexapole State-Selection of the Asymmetric-Top Molecule Propylene Oxide

A Stark Future for Quantum Control

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