Abstract
John Cowley and his group at Arizona State University pioneered the use of transmission electron microscopy for high-resolution imaging. Images were achieved three decades ago showing the crystal unit cell content at better than 4 Å resolution. This achievement enabled researchers to pinpoint the positions of heavy atom columns within the unit cell. Lighter atoms appear as resolution is improved to sub-Ångström levels. Currently, advanced microscopes can image the columns of the light atoms (carbon, oxygen, nitrogen) that are present in many complex structures, and even the lithium atoms present in some battery materials. Sub-Ångström imaging, initially achieved by focal-series reconstruction of the specimen exit surface wave, will become commonplace for next-generation electron microscopes with C(S)-corrected lenses and monochromated electron beams. Resolution can be quantified in terms of peak separation and inter-peak minimum, but the limits imposed on the attainable resolution by the properties of the microscope specimen need to be considered. At extreme resolution the 'size' of atoms can mean that they will not be resolved even when spaced farther apart than the resolution of the microscope.
| Original language | English |
|---|---|
| Pages (from-to) | 169-180 |
| Number of pages | 12 |
| Journal | Journal of Electron Microscopy |
| Volume | 54 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jun 2005 |
Funding
The first author is grateful to Professor Cowley for his guidance on the road that has led to the achievement of sub-Ångström resolution and the imaging of light atoms, and to Dr David J. Smith for critical comments on the manuscript. Electron microscopy was performed at the Advanced Microscopy Laboratory at Oak Ridge National Laboratory, and at the National Center for Electron Microscopy at Lawrence Berkeley National Laboratory. This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences Division, of the US Department of Energy, under contract No. DE-AC03-76SF00098 and the Assistant Secretary for EERE, Office of FreedomCAR and Vehicle Technology, HTML User Program, ORNL, managed by UT-Battelle, LLC for DOE (contract DE-AC05-00OR22725).
| Funders | Funder number |
|---|---|
| Materials Sciences Division | |
| Office of FreedomCar | |
| U.S. Department of Energy | DE-AC03-76SF00098 |
| Office of Science | |
| Office of Energy Efficiency and Renewable Energy | |
| Basic Energy Sciences | |
| Oak Ridge National Laboratory | DE-AC05-00OR22725 |
Keywords
- Atomic-resolution
- Exit-surface wave
- Focal-series reconstruction
- High-resolution electron microscopy
- Software aberration correction
- Sub-Ångström