Electrons photo-emitted from a sample can either be used to get a microscopic image of the sample or to map the electronic bandstructure. In our momentum microscope, we can do both. By changing the voltages of the electron lenses, we easily switch from real space to momentum space and back. Analyzing the energy and angular momentum of the sample then allows to map the complete bandstructure in 3 dimensions.
In the real space imaging, we use the instrument as a photoemission electron microscope (PEEM). When doing the bandstructure mapping, the drift tube of the microscope operates as a time-of-flight spectrometer (ToF). Additionally, the momentum microscope is equipped with a second flight tube for spin-resolution, which gives us a fourth dimesion to measure in.
During your master thesis, we will do the first measurements in the ToF operation mode of this instrument and start to set up a spin filter. The PEEM mode is already established and was used to image the photo-switching of molecular monolayers of azobenzene on gold. To start the ToF operation, a small laser setup has to be adjusted first to provide light pulses for the flight-time measurement. The investigations on switching molecules are planned to be continued during your thesis followed by first measurements on molecular spin-interfaces.
Beatrice Andres <andres[at]physik.fu-berlin.de>