Circular dichroism from non-chiral and non-magnetic materials observed with display-type spherical mirror analyzer

Abstract

Strong circular dichroism in 2-dimensional photoelectron diffraction patterns was observed for the photoelectron from the Si 2p core on the Si(001) surface using a display-type spherical mirror analyzer, although this Si(001) surface has no chirality and magnetism. The forward focusing peaks in the pattern rotate in the same direction as the incident light, i.e., clockwise or counterclockwise when the helicity of the incident circularly polarized light is reversed. These rotations of the pattern are explained by the phenomenon that the wave-front of the photoelectron wavefunction rotates as it propagates outward. This is the first direct observation of the rotation of the wavefront of the electronic wavefunction and clarifies the correspondence between the classical and the quantum mechanical ideas of angular momentum. This phenomenon offers a new possibility to measure the three dimensional surface structure.