Accurate measurement of electron beam induced displacement cross sections for single-layer graphene.

Wepresentanaccuratemeasurementandaquantitativeanalysisofelectron-beam-induceddisplacements ofcarbonatomsinsingle-layergraphene.Wedirectlymeasuretheatomicdisplacement(‘‘knock-on’’)cross section by counting the lost atoms as a function of the electron-beam energy and applied dose. Further, we separateknock-ondamage(originatingfromthecollisionofthebeamelectronswiththenucleusofthetarget atom) from other radiation damage mechanisms (e.g., ionization damage or chemical etching) by the comparison of ordinary ( 12 C) and heavy ( 13 C) graphene. Our analysis shows that a static lattice approximation is not sufficient to describe knock-on damage inthis material, while averygood agreement between calculated and experimental cross sections is obtained if lattice vibrations are taken into account.