Recent development in the appearance potential spectroscopy

Abstract The development of the appearance potential spectroscopy (APS) in the last decade is shortly reviewed. It is pointed out in which directions this method can usefully complement the information obtained by other methods of surface analysis. The possibility of determining the density of unoccupied states by deconvolution procedures and nearest neigbours arrangement by the extended APS fine structure is mentioned. Possibilities of qualitative and quantitative analysis are shown. Most interest is devoted to the study of electron excitation and transport processes inside the target. The advantage of the method consists in the fact that it is a threshold technique with excitation caused by monoenergetic primary electrons so that processes connected with excitation of particular sublevels can be distinguished. A model of the electron transport processes for DAPS and AEAPS is presented.