Physical: Letter Vortex beams for atomic resolution dichroism

Abstract Vortex beams carrying orbital angular momentum have been produced recently with electron microscopy by interfering an incident electron beam with a grid containing dislocations. Here, we present an analytical derivation of vortex wave functions in reciprocal and real space. We outline their mathematical and physical properties and describe the con-ditions under which vortex beams can be used in scanning transmission microscopy to measure magnetic properties of materials at the atomi