X-RAY-INDUCED BEAM DAMAGE OBSERVED DURING X-RAY PHOTOELECTRON-SPECTROSCOPY (XPS) STUDIES OF PALLADIUM ELECTRODE INK MATERIALS

The surface compositional characteristics of two palladium metal elect rode inks, air-dried on barium titanate (BaTiO3) dielectric ceramic su bstrates, have been studied using x-ray photoelectron spectroscopy (XP S). It is found that exposure of the inks to the x-ray beam during the time of analysis required for data acquisition causes surface damage. Changes in the C 1s and O 1s regions in particular, which reflect mod ifications to the organic, polymeric binder materials present in the i nks, have been investigated as a function of x-ray exposure time, inci dent photon energy and beam power levels. Additional complexity in the C 1s spectral envelope that cannot be explained in terms of the expec ted contributing organic functionalities is observed. This is explaine d in terms of a difference in charging effects experienced by adventit ious carbon species and those intimately associated with palladium met al centres. The degree of damage induced by the x-ray beam under speci fic operating conditions has been compared also with that caused by ex posure of the surfaces to an electron beam. Indications of the time sc ales and operating parameters for conducting XPS experiments on the un modified surface, prior to surface degradation, are given.