Low-energy ion scattering from quasicrystals

Determining whether surface atoms actually occupy fivefold symmetry sites was one of the first challenges posed following the discovery of quasicrystals. Professor Pat Thiel's group was instrumental in finding out if this is the case. They initiated a research collaboration that used low-energy ion scattering (LEIS) measurements of an Al-Pd-Mn quasicrystal to show that surface atoms indeed exist in a fivefold local environment. Subsequent work utilizing LEIS has helped us to understand the composition of the surface layer, its diffusion properties, and interactions with adsorbates. This work is reviewed, focusing on the pioneering studies of the Thiel group.