b–d, Selected-area LEED patterns taken from single-crystal domains of borophene using an electron beam focused to 1.5 μ m. The three different LEED pattern orientations correspond to three domain orientations, which can be connected by the 120° rotations. The large white rhombus corresponds to the Cu(111) substrate unit cell and the smaller yellow rhomboid defines the borophene unit cell. e–g, Selected-area LEED patterns for the three remaining domains, which are mirror symmetric with respect to those depicted in b–d. The reciprocal unit cell of borophene is shown in green. The six domains in b–g share the same structure and exhaust the observed domain orientation variety for borophene on Cu(111).