By Cameron Chai
Researchers from the Brookhaven National Laboratory of the U.S. Department of Energy (DOE) and Columbia Engineering School and scientists from the Northwestern University and DOE's Argonne National Laboratory (ANL) have involved in the development of nanocrystallography methods that can be utilized in ordinary research laboratories.
Simon Billinge (Photo credit: Eileen Barroso for Columbia Engineering)
The researchers have performed the atomic pair distribution function (PDF) analysis, a powerful technique that usually needs synchrotron x-rays or neutrons to detect a nanoparticle’s atomic structure, on a transmission electron microscope (TEM), a common laboratory instrument. They have reported about the TEM-based data-collection method and computer-modeling analyses utilized to collect quantitative nanostructural data in the Zeitschrift fur Kristallographie journal.
In the synchrotron-based technique, a sample is bombarded with an X-ray beam, whereas in the TEM-based method, an electron beam is used for this purpose to measure the interaction between the beam and the particles and excitation of atoms I in the sample. This results in a diffraction pattern, which then converted to measurements of distance distribution between pairs of particles inside a specified volume called PDF. These PDFs can then be translated to three-dimensional simulations of atomic structure using computational programs.
This research work has shown that nanparticles’ quantitatively consistent PDFs, which are hard-to-characterize utilizing standard techniques, can be extracted with the TEM under right conditions and with the proper data processing. Moreover, this technique enables a tool, which has already been utilized to get chemical information and low- and high-resolution images for nanostructures, to perform powerful atomic-scale structural arrangement analysis. This means that the same TEM can also be utilized to extract additional information.
Simon Billinge, who is the leader of the research, informed that the researchers feared that the powerful electron scattering might cause destructions in the PDF in certain cases. What surprised the researchers was these issues had impact only on some less significant structural parameters and had improved the signal, which could be used in the future to provide a higher resolution measurement. The research team is now working on ways to eliminate data processing blockades to simplify the technique for its widespread usage.