A common characteristic in semiconductor nanostructures is the lattice strain originating from the lattice mismatch between layers of different compositions. Three-dimensional strain measurement in crystals using transmission electron microscopy (TEM) techniques has been the subject of intense works for decades. This information is required for the strain-bandgap engineering being used by our current fast computers and necessary for future quantum computers. However, the missing information was the 3rd dimension that is the atomic displacement and how it changes along the electron-beam direction. The strain information along the electron-beam direction is in the phase of the diffracted beam, which has been obtained recently by the novel technique of self-interference of split higher order Laue zone line (SIS-HOLZ). SIS-HOLZ has been made possible by the correction of the beam aberrations having its analytical and experimental details reported here for the atomic displacement profile existing at the interface of a Si and Si/Si0.8Ge0.2 superlattice.

Elucidation of protein structure using X-ray crystallography relies on the quality of the crystal. Crystals suffer from many different types of disorder, some of which occur during crystal nucleation and early crystal growth. To date, there are few studies surrounding the quality and nucleation of protein crystals partly due to difficulties surrounding viewing biological samples at high resolution. Recent research has led our current understanding of nucleation to be a two-step mechanism involving the formation of nuclei from dense liquid clusters; it is still unclear whether nuclei first start as amorphous aggregate or as crystalline lattices. Our research examines this mechanism through the use of electron microscopy. Using scanning electron microscopy imaging of the protein crystal growth process, a stacking, spiraling manner of growth is observed. The tops of the pyramid-like tetragonal protein crystal structures measure ~0.2 μm across and contain ~125,000 lysozyme units. This noncrystalline area experiences strain due to growth of the protein crystal. Our work shows that it is possible to view detailed early stage protein crystal growth using a wet scanning electron microscopy technique, thereby overcoming the problem of viewing liquids in a vacuum.

A confocal scanning laser holography (CSLH) microscope that uniquely combines the concepts of confocal microscopy with holography has been validated for making nonintrusive, full three-dimensional (3D) intensity and phase measurements of objects from a single viewpoint of observation without loss of object information. The phase measurements have been used to determine the 3D refractive indices of a point source heated silicone oil. The refractive indices are converted to 3D temperature measurements, which are useful for heat transfer studies. An important feature of CSLH is its nonintrusive 3D scanning method, which enables its application to the study of Marangoni convection in microgravity with minimal operational vibrations affecting the motion of fluid in the specimen.

When electrons pass through a material, they can pass through without losing energy such as elastically scattered electrons or they can lose or gain energy by inelastically scattering with the material's electrons. The elastically scattered electrons have been used in the simulations of lattice images, which are used to help determine the atomic structure of materials. Inelastically scattered electrons were ignored in the simulations because it was believed that they did not have the required coherence to interfere with themselves and they contributed only to the background intensity. Recently though, a great deal of interest has been generated in knowing whether the inelastically scattered electrons can also contribute to the lattice images in order to help explain the Stobbs factor [1], where the contrast in the lattice images is often three or more times less than the theory predicts. The Stobbs factor makes it difficult, if not impossible, to establish quantitative values to high-resolution lattice images.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.