Medium-Energy Ion Scattering with Channeling and Blocking, MEIS

The dependence on target mass makes ion scattering techniques ideal for the study of multielement systems. By increasing the incident ion mass, the energy separation between different elements becomes larger. On the other hand, radiation-induced damage becomes a more important consideration. 

The probability for a ion to scatter in a particular direction is determined by the ion-target interaction, and can be expressed in terms of a cross section For a Coulomb potential, the diflFerential cross section is the well-known Rutherford formula  

To measure the goodness of fit, and to quantify the structural determination, a reliability (i -factor) comparison is used. In comparing the data and simulation of the experiment for many trial structures, a minimum R factor can be found corresponding to the optimal structure. In this way atomic positions can be determined in favorable cases to within a few hundredths of an A, comparable to the accuracy achieved in Low-Energy Electron Diffraction (LEED). 

Ni(IIO). The top part of the figure shows the scattering geometry. The primary ion energy was 101 keV. 

We will illustrate the power of MEIS with three simple examples. In addition, we remind the reader of the existence of extensive reviews, and in particular would like to mention some quite recent, beautifiil work on the melting of single-crystal surfaces.  

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Medium-Energy Ion Scattering with Channeling and Blocking (MEIS)... 

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