Quality of graphene on sapphire: long-range order from helium diffraction versus lattice defects from Raman spectroscopy - Anemone G; Climent-Pascual E; Yu H; Al Taleb A; Jiménez-Villacorta F; Prieto C; Wodtke A; De Andrés A; Farías D (Rsc Advances, 2016)