Nanocartography: Planning for success in analytical electron microscopy

Conclusions

The ability to precisely navigate nanoscopic volumes will become increasingly important to the field of materials science and electron microscopy. While there have been a number of researchers who have developed methodologies to predict both the stage motion of a double tilt stage and crystallographic motion and diffraction analysis, these have all typically been approached from an a priori stance where the crystallographic information is known. The research herein focuses on the approach of stage motion and crystal analysis initially where the crystal and sample are treated as physical objects with no regard for the physics of diffraction. Consideration of the vector motion, regardless of crystal type, and the structure factor as a filter to determine allowable planes/poles provides a more logical approach to mapping for both known crystalline solids as well as unknown phases. Additionally, it provides a direct relation of the crystal motion to physical constructs (such as grain boundaries) in the microscope.

With the rising cost of high-end microscopes and a push for nanoscale research, the cost-sharing model of financing purchases amongst a wide user base has put a premium on microscope time similar to that of a beamline user facility. Currently, crowd sourcing of instrumentation has become the norm due to a variety of reasons ranging from peripheral detectors approaching the price of base microscopes to ever-expanding service contracts. The more sources that pool financial resources, the higher the demand for instrumentation time. To overcome this, microscopists will be required to not only become faster and more accurate, but as well optimize every protocol available. Coupled with the increased ease of site-specific sample preparation of FIB and plasma FIB technology where a large number of samples can be prepared from all sample types, there has is a need to perform better and more efficient microscopy in order to take full advantage of collaborations between institutions. Nanocartography, mapping of TEM samples from the global scale down to the atomic column level, is a path forward to provide all researchers a manner to achieve optimal results and rapidly share information.

The necessity of nanocartography will be imperative toward the development of automated TEM. Regardless of how well automated image analysis may become, the projection aspect of TEM analysis will still require human directed analysis to a point. On the road to more automated data, collection, and analysis there must be a transition by which microscopists are provided full control to map samples. More importantly, the cost of instrumentation is an issue that will only become more complicated with automated microscopy.

Mapping of samples and optimization of data collection for each sample will be necessary for overcoming these challenges. Nanocartography is a means by which to achieve this. Data from a preliminary session be transferred to additional sessions, and samples can be shared between instruments without each microscopist having to re-map the sample. Preplanning of data analysis in between sessions could also assist in targeting desired information.