For the first time ever, scientists have recorded atoms splitting/bonding. This new method the team used could be used in the future with electronic microscopy. Image Credit: University of Nottingham)
Scientists from the University of Ulm in Germany and the University of Nottingham in the UK have managed to record a video of atoms bonding and separating for the first time. The team used transmission electron microscopy (TEM) and tools from the SALVE Project to capture the phenomenon. Their findings were published in the journal Science Advances on January 17th, 2020.
Transmission electron microscopy involves emitting a beam of electrons through an extremely thin sample, which is similar to how film photography works on a macro scale, but instead of light, TEM uses electrons. Since electrons are so tiny, it causes the resolution of a TEM image to become visible for atoms.
The team also used devices from the SALVE Project to help power their nano-scale recording, with each atom measuring ¼ nanometer across. In their recordings, it shows a pair of rhenium atoms being combined by using single-walled carbon nanotubes (SWNTs) as molecular nano-test tubes. Carbon nanotubes are typically one nanometer to a few nanometers in diameter. The electron beam helps us to see the atoms in action since the electrons move their kinetic energy to the new rhenium-rhenium molecule.
"In this case, we trapped a pair of rhenium (Re) atoms bonded together to form Re2. Because rhenium has a high atomic number it is easier to see in TEM than lighter elements, allowing us to identify each metal atom as a dark dot.", said Professor Andrei Khlobystov from the University of Nottingham.
The electron microscope doesn’t just record the experiments, but it also allows them to progress even further by using the electron energy. “We show that the simultaneous function of the electron beam as a source of energy and an imaging tool allows advancement in the understanding of metallic bonding,” the researchers write in the paper. “The metallic bond can change over time as a result of the electron beam effect.”
Even though trapping the rhenium atoms in a small carbon nanotube helped to put a focus on and record the atoms separating/bonding, it was the nanotube’s shape that also influenced what the rhenium atoms were doing. “As the bonding modes available seem to be largely influenced by the curvature of the [nanotube] wall, it is reasonable to assume that the wider nanotube with a smaller degree of curvature imposes less of a restriction on the possible bonding modes and behaves more similarly to the outside of the tube,” the team explains in the paper.
The technology has a lot of potential when it comes to recording other elements on the electron microscopic scale. Metal bonds are quite important, but it’s difficult to study metal-metal bonds and measure more critical factors about them. This is mainly because materials can interfere with and distort bond length and other important data scientists need to know to study bonds. All the bonds the scientists studied are pure metal-metal without any distortion/interference. This is because they removed all ligands from their samples.
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