Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 93: Electronic structure of surfaces: Spectroscopy, surface states III

O 93.4: Vortrag

Freitag, 13. März 2026, 10:15–10:30, HSZ/0201

Spin Polarization of Photoelectrons Excited by Deep-UV Pulses with Orbital Angular Momentum — •Paul Valerian Möllers, Ruwen Quenter, and Helmut Zacharias — Center for Soft Nanoscience, Universität Münster

It is well known that circularly polarized light can excite longitudinally spin-polarized photoelectrons from centrosymmetric crystal surfaces [1]. The light carries an angular momentum of ±ℏ, and the selection rules dictate that the photoexcitation occurs into final states with a specific total angular momentum. In the presence of spin–orbit interaction, states with different total angular momenta are energetically separated, and the excited electrons can exhibit a net spin imbalance. Light with helical wave fronts carries orbital angular momentum as a degree of freedom that is independent of its polarization and not limited to ±ℏ [2]. As the light always acts on the orbital electron angular momentum during photoexcitation, it appears plausible to assume that the optical orbital angular momentum could translate into a nonzero photoelectron spin polarization. This hypothesis has yet to be tested experimentally. We present preliminary results of spin-resolved photoemission measurements on Cu(111) and Au(111) surfaces that address this issue. [1] G. Borstel, M. Wöhlecke, Phys. Rev. B 26, 1148-1155 (1982) [2] S. S. R. Oemrawsingh et al., Appl. Opt. 43, 688-694 (2004)

Keywords: spin; optical angular momentum; Mott scattering; photoelectron spectroscopy; optical orientation