Time and Position sensitive fast piXel detectors for 4D electron spectroscopy – TPX4

Electron microscopy and spectroscopy have made spectacular progress in recent years in terms of spatial, spectral and temporal resolution. These advances have revolutionized fields ranging from biology to quantum optics.

In this context, spectromicroscopies based on electrical energy loss spectroscopy (EELS) theoretically allow access to the whole range of excitations from the far infrared (phonons) to the hard X-rays (excitons, plasmons, etc.). Thus, surface spectromicroscopy (low energy electron energy loss microscope, LEEM) and volume spectromicroscopy (scanning transmission electron microscope electron energy loss spectroscopy, STEM-EELS) are used for chemical, electronic, optical and vibrational characterization at nanometric or even atomic scales. Together with cathodoluminescence (CL), STEM-EELS has been used to perform cathodoluminescence excitation spectroscopy (CLE), a technique capable of measuring the relative quantum efficiency of materials. However, both LEEM and STEM are handicapped by the absence of detectors with temporal resolutions better than 10 ns: LEEM cannot access the relevant spectral resolutions for the study of surface vibrations, and STEM-CLE cannot access the relevant temporal resolutions for the study of excitons.

In this project, we aim to develop pixelated time-resolved detectors based on a new generation of event-based direct electrons detection, namely the Timepix4 detectors, with an unprecedented time resolution of less than 200 ps. This will allow us to access for the first time the order of the phase transition of ferroelectric surfaces and the quantum efficiency of LED materials.
The privileged access to these still non-commercial detectors, the expertise of the members in mechanics, electronics, vacuum techniques, interfacing and data processing, will allow us to develop unique High-Resolution LEEM (HRLEEM) and time-resolved STEM-TRCLE prototypes.

The detector developed in TPX4 will not be limited to STEM-TRCLE and HRLEEM applications. It could have an impact in any community concerned with the detection of photons and charged particles.