  Photoemission data taken with hard X-ray radiation on cleaved single crystals
of the barium parent compound of the MFe$_2$As$_2$ pnictide high temperature
superconductor family are presented. Making use of the increased
bulk-sensitivity upon hard X-ray excitation, and comparing the results to data
taken at conventional VUV photoemission excitation energies, it is shown that
the BaFe$_2$As$_2$ cleavage surface provides an electrostatic environment that
is slightly different to the bulk, most likely in the form of a modified
Madelung potential. However, as the data argue against a different surface
doping level, and the surface-related features in the spectra are by no means
as dominating as seen in systems such as YBa$_2$Cu$_3$O$_x$, we can conclude
that the itinerant, near-E$_F$ electronic states are almost unaffected by the
existence of the cleavage surface. Furthermore, exploiting the strong changes
in photoionisation cross section between the Fe and As states across the wide
photon energy range employed, it is shown that the degree of energetic overlap
between the iron 3d and arsenic 4p valence bands is particularly small at the
Fermi level, which can only mean a very low degree of hybridization between the
Fe 3d and As 4p states near and at E$_F$. Consequently, the itinerancy of the
charge carriers in this group of materials involves mainly the Fe 3d - Fe 3d
overlap integrals with at best a minor role for the Fe 3d - As 4p hopping
parameters, and that the states which support superconductivity upon doping are
essentially of Fe 3d character.
