Developing trends in the application of XPS in the USA

Some recent developments in XPS in the United States are briefly described. Two new instruments have been introduced, one a ‘Small Spot ESCA’, providing analyses of <1 mm area with monochromatized x‐rays, the other a conveniently engineered hemispherical analyser with very high data gathering speed and good resolution. Studies of energies of Auger lines along with those of photoelectron lines elucidate the role of screening energy in chemical shifts. Neighboring molecules, and especially neighboring conductive surfaces can provide screening energies of more than an electron volt. Effects on thin films and highly dispersed phases are beginning to emerge. Accurate data on energies and energy differences of shallow core levels and valence bands are providing information on band bending and chemical shifts at interfaces, information of great value in the semiconductor industry. Low energy monochromatized photons from synchrotron sources have provided data on shifts in core levels between surface atoms and bulk atoms. Applications in surface science are just beginning.