Electron Diffraction Intensities and Structure Analysis

A diverse array of complex materials and structures are driving the nanotechnology and molecular biology revolutions.To understand and design these materials, it is essential to perform high precision structural characterization at the nanoscale.Often,even sub-Angstrom changes in inter-atomic bond lengths have profound consequences for the chemistry and functionality of these structuresensitive materials.Crystallographic methods are the gold standard for atomic structure determination, however a broad and growing class of materials and/or nanophase morphologies do not yield to a crystallographic analysis.The scattering is diffuse and Braggpeaks become broad and overlapped.This is "the nanostructure problem" which currently has no robust solution.I will discuss recent developments using the atomic pair distribution function (PDF) analysis of x-ray and neutron diffraction data that results in quantitative structural information on the nanoscale.I will describe the data collection and modelling methods that allow this, using a number of examples from materials science, physics and chemistry.