X-ray photoelectron spectroscopy (XPS)

Abstract

X-ray photoelectron spectroscopy (XPS) is the most widely used surface analysis technique because it can be applied to a broad range of materials and provides valuable quantitative and chemical state information from the surface of the material being studied. This chapter discusses the basics of XPS where the energies of the photoelectrons, characteristic of each element, leaving the sample are determined and the peak areas can be used to determine the composition of the materials surface. Initial experimental result gives a survey scan (sometimes known as wide scan) of the binding energy spanning from 0 to 1200. eV. This will give information on the elements present in the sample. A narrow scan focusing on a specific peak or set of peaks will then be conducted to elucidate the chemical state or environment. Determination of atomic compositions in polymer membranes and the type of carbon bonding and the presence of electron withdrawing groups are discussed. The degree of cross-linking is also discussed by looking at the carbon to oxygen ratio in the polymer. Hydrophobicity and hydrophilicity are discussed by looking at the ratio of the fluorine to carbon in Nafion membranes and relating with the contact angle.