Core-level study of high-temperature superconductivity iron arsenide (Ba$_{1-x}$K$_{x})$Fe$_{2}$As$_{2}$.

We have used high-resolution x-ray photoemission spectroscopy (XPS) techniques to investigate the core-level x-ray photoemission spectra for high-temperature superconductivitor iron arsenide (Ba$_{1-x}$K$_{x})$Fe$_{2}$As$_{2}$ ($T_{C}$ = 32 K) and its parent compound BaFe$_{2}$As$_{2}$. One important issue for understanding the nature of the superconductivity in the compound is the determination of the electron-electron correlation in the system which in principle should be reflected by the appearance of core-level satellites. We have measured the temperature-dependence of Fe-$2p$ and $3s$ core-level spectrum in both parent and doped superconductor compounds and found that the core-level electronic structure is quite different from that observed in cuprates. The origin and nature of the core spectra in these iron-based materials will be discussed.