Chirality in double photoemission from a Cu(100) surface

Abstract

We investigated the double photoemission process from a Cu(100) surface with circular polarized light using coincidence spectroscopy. The handedness of the photon can be imprinted onto the emitted electron pair. The proof of this assertion lies in a helicity dependence in the electron pair intensity. We selected a photon energy that allowed the emission of the [Formula: see text] core electron. Therefore, we recorded coincidences from the [Formula: see text] electron and associated Auger electron. An additional pathway of double photoemission is the absorption of the photon by the valence band without the participation of a core electron. Adopting a chiral detection geometry, we were able to observe nonvanishing dichroism signals in both pathways of double photoemission. Hence, the emitted electron pair is chiral. Furthermore, the existence of this effect in our geometry implies that the Auger decay upon Cu [Formula: see text] excitation proceeds in a single step.