▎ 摘　　要

The structure of a graphene monolayer on Ir(111) has been investigated 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 moire-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 has proved difficult to assess in the past. The nanoripplings of graphene and iridium are found in phase, i.e., the in-plane positions of their height maxima coincide, but the amplitude of the height modulation is much larger for graphene (0.379 +/- 0.044 angstrom) than, e.g., for the topmost Ir layer (0.017 +/- 0.002 angstrom). The average graphene-Ir distance is found to be 3.38 +/- 0.04 angstrom.