Exploiting the photoelectron source wave with near-node photoelectron holography

Photoelectron diffraction patterns of a large portion of the 2 pi solid angle above a surface may be used for direct structure determination schemes such as holography. It is shown that the particular experimental set-up of near-node photoelectron holography greatly improves the quality of holographically obtained three-dimensional images of atomic arrangements. In the near-node set-up the diffraction patterns are recorded at an emission angle near the node of a photoelectron source wave and forward scattering is suppressed. 24 distinct atomic sites were observed for the test case of Al 2s (E-kin = 952 eV) diffraction from Al(111). The physics of photoelectron source waves is recapitulated and the holographic inversion procedure that is based on the multipole expansion is outlined.