Molecular Beam Deflection

Clusters in electric and magnetic fields

Schematic experimental setup.
Schematic experimental setup.

A cluster in a static electric or magnetic field interacts with the field via its electric or magnetic dipole moment. The first is sensitive to chemical bonding and in some cases to the geometric structure of the cluster while the second gives information on the electronic state of the isolated gas phase species. Experimentally, the described properties are accessible by beam deflection experiments. The clusters are produced in a laser vaporization source and a supersonic molecular beam is formed. This beam passes an inhomogeneous electric or magnetic field in which the cluster experiences a force due to the presence of an electric or magnetic dipole moment. A movable slit and an Excimer laser are used to detect the molecular beam deflection and ionize the clusters, whereas the mass distribution is analyzed by a time-of-flight mass spectrometer. A quantitative analysis of the field induced beam deflection allows extracting electric [1] or magnetic [2] dipole moments from experiment. Combined with theoretical computations, beam deflection measurements are a powerful tool to investigate the electronic and geometric structure of clusters.

[1] S. Heiles, S. Schäfer, R. Schäfer, On the rotational temperature and structure dependence of electric field deflection experiments: A case study of germanium clusters, J. Chem. Phys. 135, 034303 (2011).

[2] U. Rohrmann, S. Schäfer, R. Schäfer, Size- and Temperature-Dependent Magnetic Response of Molecular Cage Clusters: Manganese-Doped Tin Clusters, J. Phys. Chem. A 113, 12115 (2009).