Electron Impact Excitation of Metal Atoms

This experiment explores the structure and dynamics of metal atoms by using a combination of methods to observe the excitation, ionization and simultaneous excitation and ionization of free atoms. We search for the evidence of the role of spin dependent interactions, spin-orbit and exchange interactions and their interplay, momentum coupling effects, electron correlations and related to these the configuration interaction in metal atoms.

In the experiment free metallic atoms are excited by electron impact, where the incident electron energy and spin is controlled. We then observe the angular and energy dependence of the scattered or ejected electron intensity, and the polarization and intensity of decay photons. The information which we extract can be elegantly related to quantum scattering amplitudes and phases (and related parameters), which are the fundamental quantities describing the interaction. This allows theoretical models to be rigorously tested.

Source of polarised electrons

The essential ingredients for this experiment are:

• High energy resolution, variable from 50-300 meV, for both the incident electron beam and scattered electron energy analysis.
• Use of spin polarized electrons with variable polarization (0%, 30% and 75%).
• Highly accurate polarization measurements of decay photons.
• Coincident detection of electron-photon.