On the determination of carbon sp 2/sp 3 ratios in polystyrene–polyethylene copolymers by photoelectron spectroscopy

Abstract

A series of monodisperse polystyrene/polyethylene tapered block copolymers, with known carbon sp 2/sp 3 ratios, was evaluated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The principal component of the C1s peak exhibited no useful variation in shape as the sp 2 concentration was varied. The valence band spectra, however, were found to vary in a systematic manner with the sp 2 concentration. This variation was reflected in the X-ray excited C KLL Auger peak, the structure of the Auger peak providing a ready characterization of the carbon sp 2 concentration. The problem of determining the sp 2/sp 3 ratio in hydrogenated amorphous carbon is discussed.