Toroidal electron analyser

For photoemission tomography experiments we run a unique toroidal electron analyser, located permanently at the Metrological Light Source (MLS) of the Physikalisch-Technische Bundesanstalt (PTB) in Berlin.

The toroidal electron analyser [1], which was designed by John Riley and his team at La Trobe University in Australia, is very well suited for photoemission tomography, because it collects photoelectrons in a wide angular range of nearly 180°. By rotating the sample around its surface normal, the complete photoelectron distribution in a half-sphere of solid angle 2π can be recorded while the direction of light incidence with respect to the photoelectron momentum vector remains constant. When applied to photoemission tomography, the moderate energy resolution of the analyser is compensated by the wide range of accepted electron momenta.