Abstract

The electrostatic hexapole is a versatile device that has been used for many years in gas-phase experiments. Its inhomogeneous electric field has been employed for many purposes such as the selection of rotational states, the selection of clusters, the focusing of molecular beams, and molecular alignment as a precursor for molecular orientation. In the last few years, the hexapolar electric field has been demonstrated to be able to control the conformer composition of molecular beams. The key point is that conformers, where the component of the permanent electric dipole moment with respect to the largest of the principal axes of inertia is close to zero, require more intense hexapolar electric fields to be focused with respect to the other conformers. Here, we simulated the focusing curves of the conformers of 1-chloroethanol and 2-chloroethanol under hypothetical beam conditions, identical for all conformers, in a hypothetical and realistic experimental setup with three different hexapole lengths: 0.5, 1, and 2 m. The objective was to characterize this selection process to set up collision experiments on conformer-selected beams that provide information on the van der Waals clusters formed in collision processes.

Highlights

  • Electrostatic hexapoles are devices formed by six rods in metal of a length commonly included in the range of 0.5–2 m

  • Since the trajectories are strongly dependent on the dipole moment, one expects that mine the beam intensity, and a focusing curve can be obtained by plotting beam intensity molecular structures with different dipole moments, or different components of the dipole as a function of the hexapole voltage

  • Since the trajectories are strongly dependent on the dipole moment, one expects that molecular structures with different dipole moments, or different components of the dipole moment, exhibit different focusing curves

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Summary

Introduction

Electrostatic hexapoles are devices formed by six rods in metal of a length commonly included in the range of 0.5–2 m. The weak and stationary electric fields obtained by the combination of hexapolar and homogeneous direct current fields allow for the obtainment of polarized beams suitable for single or crossed molecular beam experiments [12] Applications of this technique have gained considerable success in the stereodynamic studies of inelastic collisions [13], reactive scattering [14,15], gas–surface reactions, electron transfer collisions [16,17], and photodissociation [18,19,20,21,22]. I.e., the transmitted molecular beam intensity as a function of the hexapole voltage, can drastically change depending on the components of the permanent electric dipole moment, even if their module is globally similar. About single bonds; when only one specific bond is involved, they are called rotamers [35]

Conformers and ab Initio Calculations
Asymmetric-Top Molecules
The Stark Effect
Focusing Curves and Trajectory Simulations
Results and Discussion
Focusing for the 1-chloroethanol molecular a hexapole
Focusing curves for molecular beam in a hexapole with
Conclusions
Full Text
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