Surfaces cut in the (111) direction exhibit isolated surface states, as the conduction band does not have any states with momentum along the z axis. These states however, are un localized, and very difficult to interact with via ion scattering. STM studies have shown that these surface states can be localized, by cutting the lattice such that it contains steps of (111) surfaces. These localized states might then be able to be interacted with via ion beam studies.
Johnson, P. R. and Sosolik, C. E., "Simulating Ion Scattering Trajectories on a Stepped Surface" (2019). Graduate Research and Discovery Symposium (GRADS). 266.