Photoemission spectroscopy (PES, ARPES)
Electron spectroscopy after photo-ionization constitutes a convenient tool to study the energy levels in solids, liquids and gases. In particular, angle-resolved photoemission spectroscopy (ARPES) has become invaluable for the determination of the electronic bandstructure in solids over a large range of the Brillouin zone . In combination with a pump-probe scheme empowered by femtosecond lasers, time- and angle-resolved ARPES allows to investigate the momentum-resolved relaxation of photoexcited charge carriers [2,3]. Additional insights can be obtained from ARPES microscopy .
These applications benefit from the recent advances in fiber-based femtosecond laser technology: laser pulse energies in the mJ range provide sufficient energy to drive the experiment while kHz to MHz repetition rates enable data acquisition in a timely fashion. Moreover, inner-atomic electronic levels can be excited by XUV radiation (HHG) derived from table-top laser sources. AFS offers several laser system that can drive typical photo-emission spectroscopy experiments.
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 B. Lv, T. Qian, H. Ding, "Angle-resolved photoemission spectroscopy and its application to topological materials", Nat. Rev. Phys. 1 (10), S. 609–626 (2019).
 M. Dendzik et al., "Observation of an Excitonic Mott Transition Through Ultrafast Core- cum -Conduction Photoemission Spectroscopy", Phys. Rev. Lett. 125 (2020).
 M. Ossiander et al., "Absolute timing of the photoelectric effect", Nature 561 (7723) 374–377 (2018).
 M. Keunecke et al. "Time-resolved momentum microscopy with a 1 MHz high-harmonic extreme ultraviolet beamline", Rev. Sci. Instrum. 91 (6) 63905 (2020).