Knowing the location of elements and molecules within a mixture or a solid is very important in many cases. In solids, for example, many products and processes require specific local presence of elements and molecules (e.g. in semiconductor devices, biosensors and heterogeneous catalysts). Material properties are strongly influenced by the structure, arrangements, and the boundaries of the elements and molecules. Examples are crystallographic phase, vacancies, interstitials, dislocations, molecular orientation in polymer sheets and fibers, and molecular conformation in drugs and bio-molecules.