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Chinese Physics Letters

Hexapole State-Selection and Beam Focus of Linear Triatomic Molecules

Fuchun Liu, Jin Ming-Xing, Dajun Ding

Published Apr 28, 2006• 8 citations
Publisher

Abstract

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.

DOI
10.1088/0256-307x/23/5/028

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Abstract An electrostatic hexapole lens is used to manipulate the transverse properties of a beam of barium fluoride molecules from a cryogenic buffer gas source. The spatial distribution of the beam is measured by recording state-selective laser-induced fluorescence on an emccd camera, providing insight into the intensity and transverse position spread of the molecular beam. Although the high mass and unfavorable Stark shift of barium fluoride pose a considerable challenge, the number of molecules in the low-field seeking component of the N = 1 state that pass a 4 mm diameter aperture 712 mm behind the source is increased by a factor of 12. Furthermore, it is demonstrated that the molecular beam can be displaced by up to ±5 mm by moving the hexapole lens. Our measurements agree well with numerical trajectory simulations. We discuss how electrostatic lenses may be used to increase the sensitivity of beam experiments such as the search for the electric dipole moment of the electron.
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