Nanometer Resolution Elemental Mapping in Graphene-Based TEM Liquid Cells
Journal: Nano Letters
Publication Date: 11 January, 2018
Researchers use a graphene ‘petri-dish’ to observe the movements of individual metal atoms in liquids
Studying dynamic processes in liquid environments with electron microscopy has been made possible with a graphene-based ‘nano-petri dish’. Transmission electron microscopes (TEMs) use a beam of finely focused electrons to image the structure of materials and analyse their elemental composition on the atomic scale. Usually any potential specimens must be dry, as the high vacuum inside the microscope would evaporate any fluid. This can be a major problem as the vacuum environment can change the structure of the material compared to the native state.
To overcome this, researchers at The University of Manchester have developed a method of imaging nanoparticles in water using 2D material components. This method involves adding the liquid-phase particles into wells drilled in a thin boron nitride block and then sealing it on the top and bottom with graphene. The resulting liquid-cell is similar to a standard petri-dish, though about one million times smaller, and can be used to observe specimens in liquids with single atom sensitivity and accurately map their elemental composition with nanometre-level precision. It is anticipated that this new platform will offer new perspectives into the study of nanomaterials for catalysis, optoelectronics, and bioanalysis.
- These nano-petri dishes are assembled in clean-rooms at the National Graphene Institute as even small amounts of contamination can causes big problems at the nanoscale
- The role of graphene in these cells can be compared to that of the glass in a fish-tank: it is so thin that it is transparent to the electron beam, thus minimal blurriness or distortion of the images, but at the same time strong enough to keep the water inside the cell
- The elemental composition of nanostructures can be analysed by measuring the energy of X-rays that are emitted when the electron beam interacts with atoms. The resolution for mapping these X-rays in liquid-phase samples reported here is 10 times higher than previous attempts