The first energy-resolved real-space images of the filled and empty surface states of the Si(111)-(7 x 7) surface were obtained with 3Å lateral resolution. The ability to resolve these surface states spatially, using scanning tunnelling microscopy, depended upon a new method for acquiring and separating geometrical and electronic information. The results were not only in good agreement with previous spectroscopic studies, but also revealed directly the atomic location and geometrical origin of the Si(111)-(7 x 7) surface states. Surface Electronic Structure of Si (111)-(7 x 7) Resolved in Real Space. R.J.Hamers, R.M.Tromp, J.E.Demuth: Physical Review Letters, 1986, 56, 1972-5