The HAADF-STEM (high-angle annular dark-field scanning transmission electron microscope) observation has been performed for unisize tungsten oxide clusters fixed on a carbon substrate. The exact position of each tungsten atom in the clusters has been determined successfully by analyzing the HAADF-STEM images, so that it appears that the clusters have a three-dimensional tungsten-oxide bonding network. Furthermore, the tungsten clusters are not dissociated in all the processes of the cluster preparation on the substrate by the soft-landing of size-selected tungsten cluster ions, the exposure to air, and the substrate pretreatment for the HAADF-STEM observation. However, the clusters are decomposed gradually during the HAADF-STEM observation due to the irradiation of the high-energy electron beam.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films