Images from the 3d Bands of Cu(001) In the following study, we imaged the angular distributions from the Cu 3-d bands that are located at a binding energy of 2 eV. By changing the photon energy, we were able to study their dispersion in the normal direction and the images are a cross-sectional slice through the Brillouin zone. The 45 eV slice is approximately through the center of the BZ and the 90 eV slice reaches near the top of the zone, near the X point. The 60 eV data is intermediate.

The photons are polarized in the horizontal plane with equal amounts of "s" and "p" light. The strong angular dependence is due to the coupling between emission direction, crystalline azimuthal orientation, and photon polarization. This is explained in the tight-binding calculation conducted by Gary Mankey and shown to the right of the data.

This data set shows that in any interpretation of photoemission data that does not integrate over a LARGE solid angle one must understand the

• symmetry of the state being studied
• portion of the angular pattern that is being detected
• relationship between the azimuthal orientation and photon polarization

By the way, notice how much information is located in normal-emission photoemission (the center of each image) at this binding energy? Not much, eh? Imaging the full angular distribution provides much more information.