The position structure of 23,000 atoms was first identified

For the first time, scientists can accurately determine the structural position of 23,000 atoms in a molecule smaller than a cell.

On February 1, 2017, a new method, using scanning electron microscope to probe iron - platinum nanoparticles with a diameter of only about 8.4 nano-meters (1 nano - meter = 1 / million of 1 meter), published in the journal Nature.

The author of the paper is lead researcher Peter Ercius of Lawrence Berkeley National Research Laboratory and UCLA's Jianwei Miao.

You may wonder why you should pay attention to the position of each small atom so small?

Because at the nanoscale, every atom plays an important role. Speaking of this issue in Nature, a physics professor at the German university - Duisburg-Essen, Michael Farle said: "Atoms affect nanoparticles. For example, when we change taste. The relative position of some iron atoms, platinum in a nanoparticle, iron - platinum will significantly affect the properties of particles, such as the reaction with magnetic fields ".

Take photos with eclectron beam

Electron microscopy can capture very small bits of material such as crystals or protein molecules, because electron beams can penetrate the surface of the material to capture detailed images.

Normally, when using an electron microscope to probe another large crystal or molecule, electrons will fire at the sample. As soon as they hit the sample, they will pop out and disperse, falling into the detector. Hence the arrangement of atoms in the crystal or molecule can be inferred.

3D composite version of 6,569 iron atoms and 16,627 platinum atoms in an iron nanoparticle - platinum.

However, according to Mr. Ercius, images only achieve a medium resolution with a fixed cross-section of multiple atoms at the same time. That is, the researchers only received a pattern of placement of atoms, not the exact position of each atom. And in fact, this technology is only effective for perfect structural crystals.

Iron-platinum nanoparticles are an imperfect crystal with special and uneven atomic structures. Therefore, the usual scanning method above will not produce the desired results. So scientists had to find a new solution by using electron microscopy to study iron-platinum particles from different sides.

Single atomic positioning method

To do that, the researchers changed the original position of the specimens. Instead of staying in a fixed place, they placed it on a special plane that allowed rotation and tilt of the iron-platinum particle, changing its direction a bit after each "photo" with the electron beam.

This simple change brings unexpected effects. Different directions give different patterns. The collected patterns were used to accurately calculate the positions of 6,569 iron atoms and 16,627 platinum atoms of nanoparticles.

According to Farle physicist, this research process is not the same as using animation technology to build atomic 3D models from many different angles. The resulting image of the position of the atoms according to this method achieves a resolution of about one tenth the diameter of a single atom.

In the future, such clear atomic structure images can be used in many materials science. For example, hard drive manufacturers can create small material crystals and fine structures nearly as perfect as they can easily change the magnetization level and maintain magnetic fields for a long time.

Knowing the exact location structure of each atom will also allow scientists to explore the evolution of the crystal .

Ercius said, now when running simulations of each material, they must always assume a certain development direction of the crystals, thereby helping them predict the future of the material. And if they know the position of each atom, they can make stronger judgments about the shape of the crystal as they develop completely.

Examining the chaotic arrangement of atoms not only reveals the unique nature of each object, but also provides effective effects for future material research.