Würzburg ToCoTronics Extra Seminar

Angle-resolved photoemission (ARPES) is the major experimental tool for probing the electronic structure of crystalline surfaces. ARPES has also proven very useful for oriented molecules through the so-called orbital tomography technique. When the photon energy is tuned to a core-valence resonance, the valence band information of ARPES is augmented with 
chemical and orbital selectivity inherent in the X-ray absorption step. This suggests that resonant ARPES can be used as a element-selective probe of the valence band structure of materials [1]. Although experimentally feasible, resonant ARPES is only rarely performed, presumably because of a lack of theoretical analysis tools. In this talk I will summarize our theoretical work on resonant and non-resonant ARPES. First a method for ARPES calculations based on real-space multiple 
scattering theory is introduced and results obtained for metal surfaces, graphite and organic molecules are presented with emphasis on the polarization and energy dependence of the spectra [2-4]. Second, the theory of resonant ARPES is discussed both in the framework of the independent particle approximation [5] and on the basis of many-body multiplet theory combined with scattering calculations for the emitted electron. The latter theory fully explains the recent observation of normal and reversed angular momentum transfer in resonant photoemission from a Ni surface [6].

[1] P. Krüger et al. Phys. Rev. Lett. 108, 126803 (2012).
[2] P. Krüger, F. Da Pieve and J. Osterwalder, Phys. Rev. B 83, 115437 (2011).
[3] P. Krüger, J. Phys. Soc. Japan 87, 061007 (2018).
[4] P. Krüger and F. Matsui, J Electron Spectrosc Relat Phenom, 258, 147219 (2022)
[5] F. da Pieve and P. Krüger, Phys. Rev. Lett. 110, 127401 (2013)
[6] F. Matsui et al. Phys. Rev. B 97, 035424 (2018)

This talk is also broadcasted via zoom. To enter the meeting, follow the link:
https://uni-wuerzburg.zoom.us/j/63035236463?pwd=U1FXWDJpS3JNajk4cFhoNjRDMSsvUT09