▎ 摘　　要

Using helium(-3) atom scattering, we have studied the adsorption kinetics, the structure and the diffusional dynamics of atomic hydrogen on the surface of a graphene monolayer on Ni(111). Diffraction measurements reveal a 4 degrees rotated rectangular hydrogen overstructure. Hydrogen adsorption and desorption exhibit activation barriers of E-a = (89 +/- 7) meV and E-d = (1.8 +/- 0.2) eV, respectively. Helium(-3) spin-echo measurements showed no decay of the spatial correlation function (or intermediate scattering function) within the time range of the spectrometer. Hence, we are able to set lower limits for a possible hydrogen surface diffusion rate. (C) 2016 Elsevier Ltd. All rights reserved.