A software program called Quantitative Electron Diffraction (QED) has been developed to go along with transmission electron microscopes to study the structure of crystalline materials by collecting information on the Large-Angle Rocking-Beam Electron Diffraction patterns emitted.

Crystal structure of material is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry. Patterns are located upon the points of a lattice, which is an array of points repeating periodically in three dimensions. Crystal structure is studied by transmission electron microscopes.

Transmission electron microscopes (TEM) create magnified images of samples and are, in contrast to the light microscope, even able to resolve individual atoms. When transmitting a beam of electrons through a crystalline sample such as a complex mineral or a crystallized protein, the electrons are diffracted in a specific way. Collecting such electron diffraction patterns of a sample from several different directions uniquely identifies a specific crystal structure.

Electron diffraction is a collective scattering phenomenon with electrons being (nearly elastically) scattered by atoms in a regular array (crystal). This can be understood in analogy to the Huygens principle for the diffraction of light. The incoming plane electron wave interacts with the atoms, and secondary waves are generated which interfere with each other. This occurs either constructively by reinforcement at certain scattering angles generating diffracted beams or destructively by extinguishing of beams.

LARBED (Large-Angle Rocking-Beam Electron Diffraction) patterns are composed of a series of diffraction patterns collected for a large range of directions of the electron beam. Although collected for a single specimen orientation such LARBED patterns provide 3-dimensional information and thus enable researchers to better extract information about the structure of crystalline materials in various fields of applications such as materials science, geology and life sciences.

A software program called Quantitative Electron Diffraction (QED) has been developed to analyze huge data collected from the diffraction patterns and extract information on crystal structure. The QED software can control almost any transmission electron microscope to automatically collect LARBED patterns. The new software for automated acquisition of LARBED patterns works by controlling the tilt angle and position of a collimated electron beam. The QED software compensates the beam shift with the help of the illumination system of the microscope. Thus data about characteristics from nano-sized samples can be collected. LARBED data contain an enormous amount of information about examined specimen, including specimen thickness, the absolute values of structure factors, the crystal symmetry even of very thin (<10 nm) samples, as well as the specimen surface orientation. LARBED is a patented procedure, which has been developed at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany and released by HREM Research Inc., Japan. The advantage of LARBED is that it overcomes difficulties caused by multiple scattering of electrons passing through a sample. This dynamical scattering makes it, amongst other things, difficult to analyze the intensities of the diffracted beam when using other methods based on electron diffraction. This leads to the loss of valuable information and allows transmission electron microscopes to acquire novel kinds of data, opening up new possibilities in electron crystallography.