SYNCHROTRON-RADIATION AND FREE-ELECTRON LASER-SURFACE AND INTERFACE SPECTROSCOPY AND SPECTROMICROSCOPY

Experimental breakthroughs are having a big impact on surface and interface science. We review two series of results: first, photoemission experiments performed with high (0.1 micron) lateral resolution on the scanning instrument MAXIMUM at Wisconsin. These experiments revealed, in particular, core-level shifts from place to place on cleaved semiconductor surfaces, raising serious questions about a whole class of interface formation experiments. The second series of results applied for the first time a free-electron laser (the world's brightest Vanderbilt University infrared facility) to surface and interface physics. Using the FELIPE (FEL Internal PhotoEmission) technique, we measured heterojunction band discontinuities with a few meV accuracy.