In the case of uniform coverage, whether it is bare copper or copper covered with a complete graphene layer, for any effective grazing angle αi, the reflected beam intensity profile on the detector plane in the vertical direction has a wide smooth 'bell'-like shape (Figure , black and blue curves) caused by the spread of the beam (Figure ). The scattering curves presented in Figure were obtained during growth 1 at a grazing angle αi value of 2.05°, which corresponds to a scattering vector qz = 0.8 Å -1 . The black curve in Figure is obtained on the bare liquid copper before the CVD growth of the graphene layer, and the blue curve is measured at the end of the growth when a graphene film of atomic thickness fully covers the surface under the beam. Following the calculations shown in Figure , one can see that at the qz of 0.8 Å -1 the scattering intensity from the liquid copper covered with a uniform layer of graphene is lower than the scattering from the bare liquid surface. The reason is that this position on the XRR curve is close to the minimum of the first Kiessig fringe (itself related to the height of the graphene layer above the liquid copper). The red and green curves in Figure are obtained consequently at different times of the growth (7.4 and 9.0 min after opening the CH4 valve, respectively), resulting in partial coverage of the copper surface with graphene flakes. The growth coverage was monitored in real time with radiation-mode optical microscopy. The microscopy images in Figure were taken at 7.4 and 9.0 min after opening the CH4 valve, and the start of the growth, corresponding to the red and green curves. The scattering profile of the surface with partial coverage varies between the two extreme cases of a bare and a fully covered surface. At the earlier growth stage, when graphene crystal flakes are small relative to the beam footprint and the distance between them is larger (Figure ), the major part of the scattering intensity (Figure , red curve) is defined by the scattering from the bare surface, where are only four intervals where the scattering intensity drops as four graphene flakes (at pixels 307, 374, 398, and 453) pass under the beam. With time, as CH4 continues to flow, the number of flakes and their size increase (Figure ). Consequently, the scattering contribution from graphene begins to dominate the detector profile (Figure , green curve), and thus, we see peaks of higher intensity corresponding to the regions with bare copper between graphene flakes. However, we should be careful when interpreting these data due to some possible interference effects. For example, the white centers of the flakes, most likely multilayer carbon layers stacks that get etched away at later growth stages, also introduce regions of higher intensity, as can be seen: at pixels 340 and 442 on the green curve.