Roberto Costantini
(University of Trieste)

Photoemission spectroscopy has long been a fundamental tool for materials sciences. This technique leverages the photoelectric effect – first explained by Einstein in 1905 – to eject electrons from a specimen. Depending on the incident photon energy, photoemission can occur from valence states or from the more tightly bound core levels; by analyzing the kinetic energy and angular distribution of emitted electrons, it is possible to capture a detailed snapshot of the electronic structure of matter. Core-level photoemission enables element-specific analysis of chemical environments. For instance, shifts in core-level binding energies reveal oxidation states in catalysts, surface segregation in alloys, and interfacial charge transfer in heterostructures. On the other hand, valence band photoemission can map the occupied electronic states near the Fermi level in solids, providing a direct visualization of the band dispersion.
In this lecture, I illustrate the milestones that led to establishing photoemission spectroscopy as one of the workhorses of modern condensed matter physics, discuss its basic concepts, and focus on essential aspects of this technique with a selection of examples. Building on these foundations, I will introduce the recent advancements that now enable capturing the dynamics of the excited electronic states on femtosecond timescales.
 

Zoom registration link:
https://zoom.us/meeting/register/wYAgBZV4RMeYRliYtZeNWA