Temperature-dependent high-resolution resonant photoemission study of Ce

The 4f and 5d derived states of polycrystalline Ce thin film in the alpha- and gamma-phases have been clarified in detail by means of high-resolution photoemission spectroscopy by controlling sample temperature, excitation energy, and emission angle. The Ce 4f states from the topmost atoms are evaluated by the off-normal emission (theta = 70degrees) spectra. In the alpha-phase the c-f hybridization strength at surface is weaker compared with that from deeper region while in the gamma-phase it remains almost unchanged. The ratio of the spectral intensity Ce 4f(1)/Ce 4f(0) becomes stronger from the gamma-phase to the a-phase, indicating that the c-f hybridization becomes stronger on cooling. (C) 2004 Elsevier B.V. All rights reserved.