Multi-MHz time-of-flight electronic bandstructure imaging of graphene on Ir(111)

Abstract

In the quest for detailed spectroscopic insight into the electronic structure at solid surfaces in a large momentum range, we have developed an advanced experimental approach. It combines the 3D detection scheme of a time-of-flight momentum microscope with an optimized filling pattern of the BESSY II storage ring. Here, comprehensive data sets covering the full surface Brillouin zone have been used to study faint substrate-film hybridization effects in the electronic structure of graphene on Ir(111), revealed by a pronounced linear dichroism in angular distribution. The method paves the way to 3D electronic bandmapping with unprecedented data recording efficiency.

Momentum-resolved photoelectron absorption in surface barrier scattering on Ir(111) and graphene/Ir(111)

“…The data taken in this experiment complement data measured earlier with p-polarized light for an identical sample (see, for instance, Ref. [10]). The different photon polarization manifests in different relative intensities of the bands and the position of the dark corridors.…”

“…[17] reveals that in our case the graphene layer has been grown in the R 0 orientation. This is in accordance with the momentum patterns of our earlier study [10].…”

“…3(c) clearly shows the hybridization of the graphene π band with the Ir d bands, visible at the inner basis of each triangle (oriented toward ); for details, see Ref. [10]). …”

“…The photoemission experiments were performed at BESSY II, Helmholtz-Zentrum Berlin at beamline U125-2 NIM in 8-bunch mode [10] (measurements with p-polarized light) and single-bunch mode (measurements with s-polarized light). A sketch of the experimental geometry is shown in Fig.…”

“…In the present article we analyze interference patterns appearing as dark lines in the photoemission spectra observed for graphene on Ir(111) and for clean Ir(111) using time-offlight (ToF) momentum microscopy [10]. These two samples are characterized by different topmost layers and, therefore, different surface barriers between the material and vacuum.…”