Photoemission microscopy for surface states of copper measured at different photoelectron energies

We have applied microspot photoemission spectroscopy to the surface imaging of a polycrystalline Cu plate with a lateral resolution of 0.3 μm and an energy resolution of 30 meV. The images of the crystalline islands with the (1 1 1) surface were measured by detecting photoelectrons due to the Shockley surface state (SS) and the sp-band specific to the (1 1 1) surface. The dependence of the images on the photoelectron energies was related to the mean length of the (1 1 1) terrace. The (1 1 1) island measured with the photoelectron close to the work function cutoff was found to be shifted from that measured with the Shockley state. The result demonstrates that the very high-energy resolution is essential for precise understanding of the surface images.