| AVS 63rd International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Thursday Sessions |
| Session NS+BI-ThA |
| Session: | Applied Nanoscale Microscopy Techniques/Biomaterial Interfaces – New Advances |
| Presenter: | James McBride, Vanderbilt University |
| Authors: | J.R. McBride, Vanderbilt University K.R. Reid, Vanderbilt University S.J. Rosenthal, Vanderbilt University |
| Correspondent: | Click to Email |
The key tool for the characterization of nanoparticles has long been transmission electron microscopy. This technique can provide the size, shape, crystal structure and chemical composition of a nanocrystal. Aberration-corrected Z-STEM has enabled the visualization of the true core/shell structure of colloidal quantum dots, accelerating their commercial development.1 Through dynamic STEM movies we have visualized the beam-induced motion of the surface atoms of nanocrystals and learned about the instability of the atomic structure of ultrasmall nanocrystals and the surface/sub-surface of large nanocrystals.2 However, Z-contrast can be difficult to directly interpret due to the choice in shell material or uncertainty of the 3D morphology of large, thick-shelled quantum dots. Advancements in the detector design for performing STEM energy dispersive spectroscopy mapping (STEM-EDS) have greatly facilitated the chemical imaging of nanocrystals, enabling rapid identification of their chemical structure before significant beam damage occurs. With this technological advance, we have obtained the chemical composition of an individual nanocrystal and directly correlated to its individual photophysics using our recently developed correlation technique.3 The unique combination of optical, structural and chemical information allowed us to determine the origin of the low quantum yield plaguing non-blinking CdSe/CdS quantum dots.4 Further, STEM-EDS imaging will be presented showing development of InP/CdS and Zn3N2 nanocrystals. Included in the presentation will be specifics on sample preparation and the choice of beam current/spatial resolution and sample damage.
1. McBride, J.; Treadway, J.; Feldman, L.C.; Pennycook, S.J.; Rosenthal, S.J. Structural Basis for Near Unity Quantum Yield Core/Shell Nanocrystals Nano Lett.2006, 6 (7), 1496-1501.
2. McBride, J.R.; Pennycook, T.J.; Pennycook, S.J.; Rosenthal, S.J. The Possibility and Implications of Dynamic Nanoparticle Surfaces ACS Nano2013, 7 (10), 8358-8365.
3. Orfield, N.J.; McBride, J.R.; Keene, J.D.; Davis, L.M.; Rosenthal, S.J. Correlation of Atomic Structure and Photoluminescence of the Same Quantum Dot: Pinpointing Surface and Internal Defects That Inhibit Photoluminescence ACS Nano2015, 9 (1), 831-839.
4. Orfield, N.J.; McBride, J.R.; Wang, F.; Buck, M.R.; Keene, J.D.; Reid, K.R.; Htoon, H.; Hollingsworth, J.A.; Rosenthal, S.J. Quantum Yield Heterogeneity among Single Nonblinking Quantum Dots Revealed by Atomic Structure-Quantum Optics Correlation ACS Nano2016, 10 (2), 1960-1968.