May 19 2017
A novel analysis technique is expected to bring about advancements in the understanding of nanocrystal reactions and precision of nanocrystal engineering.
Nanocrystals are composed of hundreds to thousands of precisely aligned atoms that regulate how light is absorbed and emitted. At specific light wavelengths, the crystal structure can be measured by the pattern of light absorption. Credit: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
Nanocrystals are known to have a wide range of applications spanning biomedical imaging, consumer electronics and light-emitting devices. The type of crystal from which they are composed enables them to have unique optical properties. The need for X-ray techniques in order to determine the crystal type is considered to be a significant bottleneck in the production of nanocrystals.
A novel way to determine crystal type based on optics has been developed by Researchers at the University of Illinois at Urbana-Champaign. This new technique deals with identifying the unique ways through which light is absorbed by these crystals.
This new ability eliminates the need for slow and expensive X-ray equipment, as well as the need for large quantities of materials that must be extensively purified. These theoretical and experimental insights provide simple and accurate analysis for liquid-dispersed nanomaterials that we think can improve the precision of nanocrystal engineering and also improve our understanding of nanocrystal reactions.
Andrew M. Smith, Assistant Professor of Bioengineering and Principle Investigator for the project
“The results are even more clear than with standard materials characterization methods,” stated Sung Jun Lim, a Postdoctoral Fellow in Smith’s research group and first author of the paper, “Optical Determination of Crystal Phase in Semiconductor Nanocrystals,” (DOI: 10.1038/ncomms14849) appearing in Nature Communications. “In this study, we identified optical signatures of cubic and hexagonal phases in II–VI nanocrystals using absorption spectroscopy and first-principles electronic-structure theory. We observed that high-energy spectral features allow rapid identification of phase, even in small nanocrystals around two nanometers in diameter, or just several hundred atoms.”
According to André Schleife, an Assistant Professor of Materials Science and Engineering and Co-Author of the study, that the tight integration of accurate experimentation and cutting-edge theoretical spectroscopy realized in the work is a showcase for contemporary nanoscale research. The optical crystallographic analysis technique that resulted this collaboration offers a powerful and new ability to constantly measure phase during processing or synthesis in solution by absorption spectroscopy, which can be more rapid, simple, high-throughput and potentially more suitable for structural characterization when compared with solid phase X-ray techniques.