  Wave functions and electron potentials of laterally-confined surface states
are determined experimentally by means of photoemission from stepped Au(111)
surfaces. Using an iterative formalism borrowed from x-ray diffraction, we
retrieve the real-space wave functions from the Fourier transform of their
momentum representations, whose absolute values in turn are directly measured
by angle-resolved photoemission. The effective confining potential is then
obtained by introducing the wave functions into Schroedinger's equation.
