Technique Used: ESCA (also known as XPS)
A brown-colored contaminant was found on a polyethylene part produced by a plastics manufacturer. The manufacturer suspected the contaminant to be inorganic; more specifically, it was suspected to be rust from a piece of steel in contact with the polyethylene part. Therefore, the contamination spot was analyzed using Electron Spectroscopy for Chemical Analysis (ESCA). ESCA is an excellent technique for analyzing thin films (<100 angstroms) on insulating substrates. The ESCA survey scan of the contamination on is shown in the figure below. The survey scan shows the presence of iron, magnesium, silicon, sodium, nitrogen, fluorine and oxygen on the polyethylene part. The appearance of iron and oxygen would support the possibility of rust.