Manipulating one atom at a time

20 bromine atoms positioned on a sodium chloride surface using the tip of an atomic force microscope at room temperature, creating a Swiss cross with the size of 5.6nm. The structure is stable at room temperature and was achieved by exchanging chlorine with bromine atoms. Credit: Department of Physics, University of Basel

You might remember the word IBM written by moving atoms using an atomic force microscope. That was 25 years ago, back in 1989, a the IBM labs in Zurich. An IBM fellow, Don Eigler, using a scanning tunnelling microscope moved 35 atoms of xenon in the right position to spell the word "IBM".  That was probably the beginning of nanotechnology, a way to build things one atom at a time.

Over these 25 years we have seen amazing progress but so far moving atoms around involved an electric field, which means that you can only move certain kind of atoms and move them over a conducting surface. Also, i required to operate at low temperature (as temperature rise the atoms become wiggly.... and it gets more and more difficult to get and move them).

Now a team of researchers at the University of Basel in cooperation with researchers in Finland and Japan have found a way to move atoms without using electrical fields  at room temperature and they demonstrated it by drawing a Swiss cross, as shown in the photo. They used 20 atoms of bromine and moved them using an atomic force microscope on a insulating sodium chlorine surface. The bromine atoms replaced 20 chlorine atoms to form the Swiss cross.

What is interesting here is not the cross, nor any other shape they could have decided to make but the fact that they have found a way to move atoms in a controlled way on an insulating surface at room temperature. This opens the door to study different kinds of structures that can be used in fabricating storage cells at unprecedented density, or to create electromechanical systems at the nanoscale to be used in nano-machines.

Author - Roberto Saracco

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