Graphene's unique optical properties produce an unexpectedly high opacity for an atomic monolayer in vacuum, absorbing of light, from visible to infrared. Here, "α" is the fine-structure constant. This is a consequence of the "unusual low-energy electronic structure of monolayer graphene that features electron and hole conical bands meeting each other at the Dirac point... is qualitatively different from more common quadratic massive bands." Based on the Slonczewski–Weiss–McClure (SWMcC) band model of graphite, the interatomic distance, hopping value and frequency cancel when optical conductance is calculated using Fresnel equations in the thin-film limit.