  We investigate the electronic structure of a Kondo lattice system, CeCuSb2
exhibiting significant mass enhancement and Kondo-type behavior. We observe
multiple features in the hard x-ray photoemission spectra of Ce core levels due
to strong final-state effects. The depth-resolved data exhibit a significant
change in relative intensity of the features with the surface sensitivity of
the probe. The extracted surface and bulk spectral functions are different and
exhibit a Kondo-like feature at higher binding energies in addition to the well
and poorly screened features. The core-level spectra of Sb exhibit huge and
complex changes as a function of the surface sensitivity of the technique. The
analysis of the experimental data suggests that the two non-equivalent Sb sites
possess different electronic structures and in each category, the Sb layers
close to the surface are different from the bulk ones. An increase in
temperature influences the Ce-Sb hybridization significantly. The
plasmon-excitation-induced loss features are also observed in all core level
spectra. All these results reveal the importance of Ce-Sb hybridizations and
indicate that the complex renormalization of Ce-Sb hybridization may be the
reason for the exotic electronic properties of this system.
