Tham khảo tài liệu 'handbook of analytical methods for materials part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | AUGER ELECTRON SPECTROSCOPY DESCRIPTION OF TECHNIQUE Auger Electron Spectroscopy AES provides information about the chemical composition of the outermost material comprising a solid surface or interface. The principal advantages of AES over other surface analysis methods are excellent spatial resolution 1 pm surface sensitivity 20 Ả and detection of light elements. Detection limits for most elements range from about to at . AES uses a primary electron beam to excite the sample surface. When an inner-shell electron is ejected from a sample atom by the interaction with a primary electron an electron from an outer shell fills the vacancy. To compensate for the energy change from this transition an Auger electron or an x- ray is emitted. For light elements the probability is greatest for the emission of an Auger electron which accounts for the light-element sensitivity for this technique. The energy of the emitted Auger electron is characteristic ofthe element from which it was emitted. Detection and energy analysis of the emitted Auger electrons produces a spectrum of Auger electron energy versus the relative abundance of electrons. Peaks in the spectrum identify the elemental composition ofthe sample surface. In some cases the chemical state of the surface atoms can also be determined from energy shifts and peak shapes. Auger electrons have relatively low kinetic AES Spectrum for Passivated Stainless Steel energy which limits their escape depth. Any Auger electrons emitted from an interaction below the surface will lose energy through additional scattering reactions along its path to the surface. Auger electrons emitted at a depth greater than about 2 - 3 nm will not have sufficient energy to escape the surface and reach the detector. Thus the analysis volume for AES extends only to a depth of about 2 nm. Analysis depth is not affected by the energy of the primary electron energy. The AES instrumentation can include a tungsten filament or field emission .
