| 1. |
- Nilsson, Sara, 1990, et al.
(författare)
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Probing the role of grain boundaries in single Cu nanoparticle oxidation by in situ plasmonic scattering
- 2022
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Ingår i: Physical Review Materials. - 2475-9953. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- Grain boundaries determine physical properties of bulk materials including ductility, diffusivity, and electrical conductivity. However, the role of grain boundaries in nanostructures and nanoparticles is much less understood, despite the wide application of nanoparticles in nanophotonics, nanoelectronics, and heterogeneous catalysis. Here, we investigate the role of high-angle grain boundaries in the oxidation of Cu nanoparticles, using a combination of in situ single particle plasmonic nanoimaging and postmortem transmission electron microscopy image analysis, together with ab initio and classical electromagnetic calculations. We find an initial growth of a 5-nm-thick Cu2O shell on all nanoparticles, irrespective of different grain morphologies. This insensitivity of the Cu2O shell on the grain morphology is rationalized by extraction of Cu atoms from the metal lattice being the rate limiting step, as proposed by density functional theory calculations. Furthermore, we find that the change in optical scattering intensity measured from the individual particles can be deconvoluted into one contribution from the oxide layer growth and one contribution that is directly proportional to the grain boundary density. The latter contribution signals accumulation of Cu vacancies at the grain boundaries, which, as corroborated by calculations of the optical scattering, leads to increased absorption losses and thus a decrease of the scattering, thereby manifesting the role of grain boundaries as vacancy sinks and nuclei for Kirkendall void formation at a later stage of the oxidation process.
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| 2. |
- Spackova, Barbora, 1979, et al.
(författare)
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Label-free nanofluidic scattering microscopy of size and mass of single diffusing molecules and nanoparticles
- 2022
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Ingår i: Nature Methods. - : Springer Science and Business Media LLC. - 1548-7091 .- 1548-7105. ; 19, s. 751-758
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Tidskriftsartikel (refereegranskat)abstract
- Nanofluidic scattering microscopy enables label-free, quantitative measurements of the molecular weight and hydrodynamic radius of biological molecules and nanoparticles freely diffusing inside a nanofluidic channel. Label-free characterization of single biomolecules aims to complement fluorescence microscopy in situations where labeling compromises data interpretation, is technically challenging or even impossible. However, existing methods require the investigated species to bind to a surface to be visible, thereby leaving a large fraction of analytes undetected. Here, we present nanofluidic scattering microscopy (NSM), which overcomes these limitations by enabling label-free, real-time imaging of single biomolecules diffusing inside a nanofluidic channel. NSM facilitates accurate determination of molecular weight from the measured optical contrast and of the hydrodynamic radius from the measured diffusivity, from which information about the conformational state can be inferred. Furthermore, we demonstrate its applicability to the analysis of a complex biofluid, using conditioned cell culture medium containing extracellular vesicles as an example. We foresee the application of NSM to monitor conformational changes, aggregation and interactions of single biomolecules, and to analyze single-cell secretomes.
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