Photoelectron Spectroscopy (PES) is a technique where the sample is illuminated with light of a certain frequency, releasing electrons from the surface, which can be analysed in an electron spectrometer to give a spectrum of their energy.
The spectrum produced contains peaks which are characteristic of the chemical composition of the surface. Angular Resolved Photoemission Spectroscopy (ARPES) is an extension of PES, where the angular distribution of the emitted electrons is also measured.
The emission angle of the electrons is determined by the in-plane momentum of the electron within the surface and can be used to obtain useful information about the electron band structure of the material.
Modern spectrometers such as the Kreios from our partner, SPECS, offer the following benefits:
-Analysis of a much wider range of emission angles than traditional spectrometers (up to the full +/-90 degrees) vs traditional passive spectrometers where limits can be as low as +/- 15 degrees.
- Data collection from small surface areas down to 2 microns. A new field of µARPES (momentum microscopy) is opened up by such analysers due to their enhanced spatial resolution, so far only possible on synchrotron beamlines with special photon optics.