Angle-resolved photoemission: From reciprocal space to real space

The prospects for converting angle-resolved photoemission data from reciprocal space to real space are evaluated. Examples are given for one- and two-dimensional systems, where wave functions have been obtained for quantum well states confined between steps and for planar molecules adsorbed at a surface. The extension to three-dimensional systems via variable photon energies is discussed. The uncertainty relation between position and momentum makes such a capability complementary to imaging in real space by scanning tunneling microscopy. Angle-resolved photoemission provides access to the internal structure of an electronic orbital and penetrates below the surface.