Time- and angle-resolved photoemission (TR-ARPES)
ARPES relies on the photoelectric effects, i.e. the emission of an electron via the absorption of ultraviolet light. By detecting the angle of emission and kinetic energy of photoelectrons, we offer direct insights into electronic properties and collective excitations of complex quantum materials.
The extension of the momentum space (and the related band dispersion) explored via ARPES is directly proportional to the photon energy of the ultraviolet light (see figure on the right). The TR-ARPES endstation at ALLS uses low-energy (6 eV) and high-energy pulses (>15 eV) in an effort to map the momentum space of quantum materials.
ARPES is extended into the time domain (TR-ARPES) via pump-probe stroboscopic technique: an ultrashort intense pulse (the pump) is used to excite the system under investigation, while a delayed ultraviolet pulse (the probe) photoemites electrons. By changing the relative delay between pump and probe, a movie of the femtosecond electron dynamics inside the material is recorded. [see Rev. Mod. Phys. 96, 015003 (2024)].
The figure on the left displays key classes of quantum materials studied via TR-ARPES
Boschini, Zonno, Damascelli
Rev. Mod. Phys. 96, 015003 (2024)