L. Kyhla, T. Angotb, L. Hornekaera,c, R. Bissonb
a) Interdisciplinary Nanoscience Center, Aarhus University
b) PIIM/CNRS Aix-Marseille Université, France
c) Institute of Physics and Astronomy, Aarhus University, Denmark
The electronic and structural properties of hydrogenated graphene on Ir(111) have previously been studied using scanning tunneling microscopy (STM) and angle resolved photoemission spectroscopy (ARPES) . These techniques show nanostructured hydrogenation, templated by the moiré structure and opening of a gap around the Fermi level of at least 450 meV . Two different hydrogen adsorption configurations on graphene on Ir(111) are still under debate [2, 3]: i) Hydrogen adsorbs on the top (vacuum) side of the graphene sheet, stabilized by the formation of carbon-iridium bonds on the bottom (iridium) side of the graphene; a graphane-like conformation. ii) Chemisorption of hydrogen is stabilized by the hydrogen atom adsorption on both sides of the graphene sheet; real graphane.In this work hydrogen atom adsorption on high-quality graphene on Ir(111) was investigated using high-resolution electron energy loss spectroscopy (HREELS). No evidence was found for hydrogen bound on both sides of a high quality graphene sheet and phonon features strongly suggest increased interactions between carbon and iridium atoms upon hydrogen atom exposure The presented results lead to the conclusion that hydrogen atoms bind only on the top side of high-quality graphene on Ir(111).
Line Kyhl is currently a PhD student in Nanoscience at iNANO, Aarhus University.