Diffusion of Si atoms in Pd under energetic ion irradiation was studied in Pd film (100nm)-coated Si using synchrotron radiation X-ray photoelectron spectroscopy. Before irradiation, photo-electron spectra were observed only for Pd; with no trace of Si. After irradiation with 3MeV Si ions or 1MeV O ions, an additional photo-electron component was observed at a binding energy of 2.2 to 2.9eV higher than that of Si 1s bulk component. This experimental result implied that energetic-ion bombardment induced the diffusion of Si atoms from the Si–Pd interface to the Pd layer surface. From the shift of the binding energy, the chemical state of Si atoms at the Pd surface was deduced.

Observation of Ion-irradiation Induced Diffusion in Pd–Si System using Synchrotron Radiation X-Ray Photoelectron Spectroscopy. A.Iwase, Y.Chimi, N.Ishikawa, R.Nakatani, Y.Kato, M.Fukuzumi, H.Tsuchida, Y.Baba: Nuclear Instruments and Methods in Physics Research B, 2006, 245[1], 141-4