  The quantum well states of a film can be used to sample the electronic
structure of the parent bulk material and determine its band parameters. We
highlight the benefits of two-dimensional film band mapping, with respect to
complex bulk analysis, in an angle-resolved photoemission spectroscopy study of
the 5d states of Au(111). Discrete 5d-derived quantum well states of various
orbital characters form in Au(111) films and span the width of the
corresponding bulk bands. For sufficiently thick films, the dispersion of these
states samples the bulk band edges, as confirmed by first-principles
calculations, thus providing the positions of the critical points of bulk Au in
agreement with previously determined values. In turn, this analysis identifies
several d-like surface states and resonances with large spin-splittings that
originate from the strong spin-orbit coupling of the Au 5d atomic levels.
