2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/137253A method is suggested to separately determine the surface density of positively and negatively charged impurities that limit the mobility in a graphene monolayer. The method is based on the exact result for the transport cross-section, according to which the massless carriers are scattered more strongly when they are attracted to a charged impurity than when they are repelled from it.3 pages, 1 figureMesoscale and Nanoscale PhysicsMaterials Sciencetext