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Using lasers to cut a diamond apart atom by atom

One of great challenges of the 21st century has been to develop ways to manipulate matter on smaller and smaller dimensions. As the great physicist Richard Feynman noted in his famous 1959 lecture, “There’s…

Diamonds are the first material to have single atoms removed by a laser. Africa Studio

One of great challenges of the 21st century has been to develop ways to manipulate matter on smaller and smaller dimensions.

As the great physicist Richard Feynman noted in his famous 1959 lecture, “There’s plenty of room at the bottom”, and this adage is currently playing out with unprecedented vigour.

Nanomachines, quantum computing components and ultrafast electronics are all important areas that are benefiting from this extreme push for engineering on the ultra-nanoscale.

How small can you cut?

To date, lasers have been tremendously successful tools for manipulation of matter on small scales but only to a certain point. Despite their ability to drill and cut materials to within a human hair’s width, they have notoriously poor resolution on the atomic scale.

The fundamental reason for this is that conventional laser machining relies on heating the material, with atoms ejected from the surface by the resulting explosive forces and vaporisation. As a result, many atoms get caught up in the process making it impossible to achieve the resolution needed – it is like trying to pick out a grain of salt using a blow torch.

Improving resolution was thought to be a rather hopeless situation. But there now seems to be a new pathway forward, at least for some materials.

We have now discovered that lasers can be made to split apart the chemical bonds holding atoms together without any significant collateral damage into the surrounding material.

Focus on diamonds

The critical experiment involved an ultraviolet laser beam on a diamond surface.

UV laser beam on synthetic diamond. Andrew Lehmenn, Daniel Price and Rich Mildren

It was found that the probability for ejection of the carbon atoms that comprise the crystal lattice was sensitive to the laser beam’s polarisation (that is, the direction of the light wave’s beating movement) with respect to the direction of chemical bonds that hold the material together.

In the chaotic environment of a laser heated surface, this kind of selective atom removal hasn’t been feasible.

Like many good scientific discoveries, this one was discovered entirely by accident.

On close examination of surfaces exposed to a UV laser we observed regular nano-patterns of size on the molecular scale. The key observation, reported in Nature Communications today, is that the shape and orientation of these patterns are dependent on the alignment of the laser polarisation with the way atoms line up in the crystal lattice.

Electron microscope image of the nano-scale etch pattern on diamond created by the UV laser treatment. Rich Mildren

As laser polarisation was altered a rich variety of patterns were produced. Some were reminiscent of natural forms such as ripples on the beach (picture above), and revealing partial images of the underlying symmetries contained in the arrangement of atoms that make up the crystal.

Take that, atom by atom

The results show for the first time that a laser beam can target specific atoms on the surface, in a way not yet entirely understood, causing their chemical bonds to break before there is any significant dissipation of energy into the surrounding area.

The laser hits the diamond surface and releases the atoms. Chris Baldwin

The significance of the result is that it is possible for lasers to interact with pairs of atoms and cause their separation without disturbing the surroundings. In the case of diamond, we used light polarisation to select what atom pairs are targeted by the laser beam.

That this effect has been first achieved in diamond is very convenient. Diamond is a material that, although it’s been available in raw form for millennia, is only now gaining great importance in science and technology. This recent surge in interest is a result of low-cost production of high-quality diamond material from synthetic sources.

Potential uses of such a small cut

This discovery can therefore be readily exploited in the many cutting-edge areas of diamond technology such as for fabrication of quantum processors and miniature high-power lasers.

So far the effect has been seen across the broad area of the laser beam. Although this may be useful in itself for rapid nano-texturing of surfaces, for example, a major focus of future research is to demonstrate the ultimate control of single atoms on a surface.

Individual atoms manipulated to spell out a name. IBM

About 25 years ago, IBM in the US demonstrated the ability to construct alphabet characters out of single atoms on the surface of a metal using the sharp tip of scanning probe microscope.

But in that instance, and in much other related work since, this procedure only works for atoms that are very weakly bound to the surface. Now, we have the exciting prospect being able to manipulate the strong atomic bonds that make up a solid including super-strongly bonded materials like diamond.

It is likely that the fact we observed this effect in diamond is no coincidence since this is a material with very highly defined bonds that are relatively disconnected from neighbouring atoms.

The key question now is – how many other materials reveal this effect?

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3 Comments sorted by

  1. Dale Bloom


    The diamond crystal lattice has one carbon atom forming covalent bonds with two other carbon atoms.

    It appears the laser is supplying sufficient energy to break the covalent bonds between atoms, to basically create separate carbon atoms.

    But I am not certain how the laser energy is not sufficient to over-excite electrons in the outer shell of each carbon atom, and these electrons then break free leaving behind carbon cations.

    The ability to easily and economically break the covalent bonds between oxygen and hydrogen atoms in a water molecule would mean the ability to create a ready fuel, as the hydrogen atoms could be separated and then recombined with oxygen atoms through combustion to again create a water molecule.

    Perhaps not economic in an energy sense to be able to do this.

    1. Robert Klaassen

      logged in via email

      In reply to Dale Bloom

      The diamond has four not two covalent bonds in a face centred cube. I expect the lack of symmetry at the surface of the tetrahedron may have something to do with the surface layer having different properties to the more stable bonds tightly bound in the crystal lattice. The discovery may also have implications for controlled deposition of vapours into crystalline solids.

    2. Dale Bloom


      In reply to Robert Klaassen

      A carbon atom has 4 valence electrons, and there are two double covalent bonds between carbon atoms in the crystal lattice of diamond.

      That makes the structure very strong.

      But if the laser provides enough energy to break the double covalent bonds, it should also energise the outer shell electrons so much they spin off the atom, leaving behind carbon cations.