It’s not possible for anyone to bullet through a banana so that the skin is punctured however the banana stays unblemished. In any case, fair and square of individual atomic layers, scientists at TU Wien (Vienna) have now accomplished such an accomplishment—they built up a nano-organizing strategy with which certain layers of material can be punctured very correctly and others left totally immaculate, despite the fact that the shot enters all layers.This is made conceivable with the assistance of exceptionally charged particles.
They can be utilized to specifically process the surfaces of novel 2-D material frameworks, for instance, to stay certain metals on them, which would then be able to fill in as impetuses. The new technique has now been distributed in the diary ACS Nano.
New materials from ultra-thin layers
Materials that are made out of a few ultra-slight layers are viewed as an energizing new field of materials research. The superior material graphene, which comprises of just a solitary layer of carbon atoms, has been utilized in numerous new slender film materials with promising new properties.
“We investigated a combination of graphene and molybdenum disulfide. The two layers of material are brought into contact and then adhere to each other by weak van der Waals forces,” says Dr. Janine Schwestka from the Institute of Applied Physics at TU WIen and first creator of the current distribution. “Graphene is a very good conductor, molybdenum disulphide is a semiconductor, and the combination could be interesting for the production of new types of data storage devices.”
For specific applications, be that as it may, the geometry of the material should be explicitly prepared on a size of nanometres—for instance, so as to change the concoction properties by including extra kinds of iotas or to control the optical properties of the surface.
“There are different methods for this,” clarifies Janine Schwestka. “You may modify the surfaces with an electron beam or with a conventional ion beam. With a two-layer system, however, there is always the problem that the beam affects both layers at the same time, even if only one of them is supposed to be modified.”
Two sorts of energy.
At the point when a particle shaft is utilized to treat a surface, it is normally the power of the effect of the particles that influences the material. At TU Wien, be that as it may, generally moderate particles are utilized, which are duplicate charged. “Two different forms of energy must be distinguished here,” clarifies Prof. Richard Wilhelm.
“On the one hand, there is the kinetic energy, which depends on the speed at which the ions impact on the surface. On the other hand, there is the potential energy, which is determined by the electric charge of the ions. With conventional ion beams, the kinetic energy plays the decisive role, but for us, the potential energy is particularly important.”
There is a significant contrast between these two types of vitality: While the dynamic vitality is discharged in both material layers while infiltrating the layer framework, the potential vitality can be conveyed unevenly among the layers: “The molybdenum disulfide reacts very strongly to the highly charged ions,” says Richard Wilhelm. “A single ion arriving at this layer can remove dozens or hundreds of atoms from the layer. What remains is a hole, which can be seen very clearly under an electron microscope.”
The graphene layer, then again, which the shot hits promptly a while later, stays flawless: the greater part of the potential vitality has just been released.
A similar trial can likewise be turned around, with the goal that the exceptionally charged particle first hits the graphene and at exactly that point the molybdenum disulphide layer.
For this situation, the two layers stay unblemished: The graphene furnishes the particle with the electrons important to kill it electrically in a small division of a second.
The versatility of the electrons in the graphene is high to such an extent that the purpose of effect additionally “cools down” right away. The particle crosses the graphene layer without leaving a perpetual follow. A while later, it can no longer reason a lot of harm in the molybdenum disulphide layer.
“This provides us now with a wonderful new method for manipulating surfaces in a targeted manner,” says Richard Wilhelm. “We can add nano-pores to surfaces without damaging the substrate material underneath. This allows us to create geometric structures that were previously impossible.” thusly, it is conceivable to make “masks” from molybdenum disulfide punctured precisely as wanted, on which certain metal atoms are then saved. This opens up totally additional opportunities for controlling the substance, electronic and optical properties of the surface.