The structure of a graphene monolayer on Ir(111) has been investigated {\it in situ} in the growth chamber by surface x-ray diffraction including the specular rod, which allows disentangling the effect of the sample roughness from that of the nanorippling of graphene and iridium along the moir{\'e}-like pattern between graphene and Ir(111). Accordingly we are able to provide precise estimates of the undulation associated with this nanorippling, which is small in this weakly interacting graphene/metal system and thus proved difficult to assess in the past. The nanoripplings of graphene and iridium are found in phase, i.e. the in-plane position of their height maxima coincide, but the amplitude of the height modulation is much larger for graphene (0.379±0.044 \AA) than, {\it e.g.}, for the topmost Ir layer (0.017±0.002 \AA). The average graphene-Ir distance is found to be 3.38±0.04 \AA.
@article{arxiv.1506.07492,
title = {Topography of the graphene/Ir(111) moir{\'e} studied by surface x-ray diffraction},
author = {Fabien Jean and Tao Zhou and Nils Blanc and Roberto Felici and Johann Coraux and Gilles Renaud},
journal= {arXiv preprint arXiv:1506.07492},
year = {2015}
}