739 publications from this institution
A common limitation in nanostructure research is often the requirement to perform experiments on ensembles of nanoparticles, therefore averaging over inherent distributions with respect to particle size and shape, chemical composition, crystallinity and defect structure. This limitation can be overcome by studying the properties of a single nanostructure individually, which will allow one to truly correlate scaling laws of material properties with changes in size. Here we report the first experiments to explore the feasibility of spectromicroscopy using a photoemission electron microscope (PEEM) to record the X-ray absorption spectra of single nanocrystals. Colloidal iron oxide nanocrystals with an average diameter and standard deviation of 13 nm and 2 nm, respectively, were deposited on graphite (HOPG) forming small islands of agglomerated γ- Fe 2 O 3 nanocrystals (4–30 particles) as determined by scanning electron microscopy. Spatially resolved soft X-ray absorption spectra at the Fe L 3,2 edges of these individual islands were recorded with the PEEM2 instrument of the Advanced Light Source (ALS).
Abstract The interplay between crystallization and chirality has fascinated chemists for over 170 years now. Many questions deal with the transfer of chirality from molecular level building blocks and crystal capping ligands to the macroscopic morphologies of crystals. Also the interest in nanoscale chiral crystallization and the relationship between chiral ligands and inorganic nanocrystals has recently arose. In this review we highlight several different topics related to studies of the interplay between chirality and crystallization that involve inorganic nanocrystals. Specifically, we differentiate between the effects of chiral molecules on inorganic nanocrystals with chiral or achiral crystal structures. In the first case, chirality may appear both at the atomic‐scale and the particle shape, and in the second case chirality may be induced only at the particle shape level. We also discuss recent progress on the relationship between the atomic scale chirality and crystal morphology.
