A surface-sensitive technique capable of detecting all elements with an atomic number greater than that of helium. ESCA provides data on the outermost several atomic layers of a material, and has a sensitivity in the order of 0.5 atomic percent. A primary advantage of ESCA is that it can both determine and quantify the chemical state of the elements detected (i.e. metallic state or oxide state). Also known as Electron Spectroscopy for Chemical Analysis (ESCA).