Elastic Backscattering of Ions for Compositional Analysis

摘要: Composition analyses for all of the elements in periodic table can be performed through a combin¬ation techniques using ion beams at MeV energies (MeV-IBA: see INTRODUCTION TO ION BEAM TECHNIQUES) including PIXE, RBS, EBS, ERD, NRA. See also PARTICLE SCATTERING and ATOMIC EXCITATION METHODS COMMON CONCEPTS chapter. In this unit we consider elastic backscattering techniques: Rutherford spectrometry; (non-Rutherford) backscattering. following Rutherford's treatment 1911 Geiger & Marsden's 1909 alpha-scattering experiment, approximates scattering cross-section by that expected Coulomb interaction point charges. This approximation is valid providing interacting nuclei do not come too close during interaction. As energy increased fails, quantum mechanical effects become visible: then called "EBS". BS (elastic spectrometry, either RBS or EBS) used to obtain elemental depth profiles thin films up ~10 m thick. Depth resolution degrades with but ~1 nm surface. Various various beam selected optimal analytical conditions particular samples. Barbour's article was on "Elastic Scattering", which included important ERD technique now covered separately (see: ELASTIC RECOIL DETECTION ANALYSIS). We will mention use microbeams since many samples are small laterally non-homogeneous, microbeam IBA reviewed TOMOGRAPHY. channelling geometries characterising defects single crystal samples, extensively MEDIUM-ENERGY ANALYSIS. should LEIS MEIS both techniques, they low (see, respectively, LOW-ENERGY The Wiley Characterisation Materials book part has section Ion Beam Analysis TECHNIQUES section). 2002 edition treated independently, 2012 treat them synergistically. present considers details analysis particle detector placed direction. explicitly distinguish between even though any spectrum there may (and often are) EBS signals: philosophical difference signal resulting from an accurately approximated one must mechanically.