  We investigate the role of ligand states in the electronic properties of
CaFe2As2 using high-resolution hard x-ray photoemission spectroscopy (HAXPES)
at different sample temperatures. Experimental results indicate that the
binding energy of Ca is close to that for 2+ charge state of Ca atoms and the
other constituent elements, Fe and As possess electronic configuration close to
that in elemental systems. No difference is observed in the As 3p core level
spectra with the change of emission angle and/or the change in sample
temperature. This is surprising as the Ca atoms at the cleaved sample surface
reorganizes itself to form linear structures which is expected to influence
Ca-As hybridization leading to significant difference in surface and bulk
electronic structures. Moreover, CaFe2As2 undergoes structural and magnetic
phase transition at 170 K, and strong Fe-As hybridization provides pathways for
electron dynamics. Clearly, further studies are required to resolve these
puzzling observations.
