Giovanni Zamborlini
Photoemission electron microscopes (PEEMs) are powerful and versatile tools for investigating the chemical and physical properties of surfaces with spatial resolution. Thanks to their electron lens system, they can capture both spatial and angular information of photoemitted electrons in a single acquisition, enabling the measurement of momentum distribution of photoelectrons across the first Brillouin zone from selected areas of the surface, typically just a few micrometers wide. This enables access to the material’s band structure from micrometer size flakes. PEEMs can also be coupled with pulsed light sources, such as high-harmonic generation or UV-pulsed sources, in a pump-probe setup, allowing for time-resolved experiments with femtosecond resolution. Furthermore, by incorporating an electron mirror into the optical path, it is possible to probe the photoelectron momenta with spin resolution.
In this talk, I will showcase how the capabilities of PEEM instruments can be fully exploited to unravel the electronic structure, spin texture, and electron dynamics of selected systems through three distinct examples. First, I will demonstrate that passivating an iron surface with atomic oxygen significantly modifies the electronic properties of the pristine surface, enhancing electron correlation. The non-trivial spin texture of this system can be investigated with our PEEM using spin- and angle-resolved photoemission electron spectroscopy (spin-ARPES), while the findings can be rationalized through state-of-the-art theoretical methods that go beyond the one-electron approximation to include the effects of electron correlation [1]. Next, I will highlight the setup’s ability to perform time-resolved ARPES (tr-ARPES) in a pump-probe configuration while maintaining near state-of-the-art momentum space resolution. This capability is benchmarked through a series of tr-ARPES experiments on bismuth selenide (Bi₂Se₃) and WS₂ (the latter both in bulk and monolayer crystal forms) [2,3]. Finally, I will illustrate how ARPES measurements benefit from a full-field acquisition scheme, enabling the probing of energy level alignment at the molecular/WS₂ interface.
[2] S. Ponzoni et al. Advanced Physics Research 2, 2200016 (2023).
[3] K. Schiller et al. Scientific Reports, just accepted, DOI: 10.1038/s41598-025-86660-1 (2025).