The change in focus of a high-resolution electron microscope is generally assumed to be linear with change in objective lens current. Thus the defocus step size should be constant for a constant step in lens current. Measurements on the LBNL One-Angstrom Microscope show that the step size increases with increasing underfocus (reduced lens current). Differentiation of the best-fit quadratic shows that the defocus step size varies linearly as defocus changes.

We have used the One-Angstrom Microscope (OAM) to image and apply focal-series reconstruction (FSR) of the exit-surface wave (ESW) to a 70Angstrom particle of gold supported on amorphous carbon. The phase of the complex ESW shows the positions of the atom columns in the specimen as white dots, and its diffractogram shows it contains information to 1.23Angstrom. The result demonstrates that through-focal reconstruction of the ESW does not need large crystal expanses to work properly. Although [110] Au structures may not need sub-Angstrom resolution to show all the useful structural details of the particle in this orientation, it is clear that focal reconstruction of the ESW can improve original data that is much more difficult to interpret directly. We expect this technique to prove even more useful when applied to nanoparticles containing finer spacings than the 2.35Angstrom separation of the 111 planes in the present gold nano-particle.

Phase-contrast imaging in the high-resolution electron micrscope produces images with peaks at atom positions by extracting the spatial distribution of the relative phase from the electron wave. Usually, the electron wave is imaged by direct interference of diffracted beams at optimum focus. Instead, the One-Angstrom Microscope uses focal-series reconstruction software to derive the relative electron phase from a series of images taken over a range of focus, with peaks that correspond to the atom positions at a resolution that extends to the microscope information limit. Tests using a silicon specimen tilted into [112] orientation show that the O Angstrom M has achieved a world-record resolution of 0.78 Angstrom.

LiCoO2 is the most common lithium storage material used as positive electrode in lithium rechargeable batteries. Ordering of lithium and vacancies has a profound effect on the physical properties of LixCoO2 and the electrochemical performances of lithium batteries. An exit surface wave (ESW) phase image reconstructed from experimental images obtained on the LBNL One-Angstrom Microscope (OAM) shows all three types of atoms in LiCoO2.