▎ 摘　　要

We show that graphene is best described as a slab with finite thickness based on our reflectivity analysis for five different wavelengths. We perform fine-scan angular reflectivity on a single layer graphene on top of SiO2/Si and determine its crossing angle. The experimental data were then compared to the predictions of the three most common models for a single layer graphene. We find that the slab model gives good predictions for the crossing angle in all our experiments. This implies that (1) the real part of the electric permittivity of graphene has a crucial role in the electromagnetic wave propagation, (2) the field across a single layer graphene is continuous, and (3) the dispersionless refractive index of graphite can describe the optical index of graphene in the visible regime. (C) 2019 Elsevier Ltd. All rights reserved.