French nanotech researchers have used theory to increase the precision of carving with electron beams enough to remove individual atoms from single walled carbon and boron nitride nanotubes.
Over in Nanowerk Spotlight, researcher Alberto Zobelli describes progress in the top-down approach to atomically precise manufacturing (APM) that he and his coworkers recently achieved. From “‘Nanosculptors’ carve atom by atom“:
They [referring to himself and his coworkers] have developed a new approach to shaping nanomaterials atom by atom, using a scanning transmission electron microscope (STEM) as a nanometrically precise cutting tool. In this way they ‘carve’ their materials, such as carbon nanotubes, by removing individual atoms from specifically chosen locations. This technique has the added advantage that scientists can observe what they are doing at the same time. The new technique demonstrates a ‘nanoelectron-lithography’ of single walled nanotubes, a top down approach to locally control their nanostructures.
…The possibility of controlled reshaping of nanotubes could have a strong technological impact. The removal of one line of atoms in a nanotube changes the chirality of the tube and consequently its electronic character locally. For specific initial chiralities we might be able to switch from metal to semiconductor or vice versa: a good way to produce a Schottky diode at the nanoscale! Another application lies in the use of defects as chemically active sites; our ability to control the spatial distribution of defects on nanotubes could be used as a post synthesis way of controlling chemical functionalization.
…Last month, our Orsay laboratory has been equipped with a new generation STEM microscope mounted with a spherical aberration corrector, which produces previously unachievable probe sizes as low as just 1 Ångström [1 Å = 0.1 nm]. We expect to open a new frontier in electron irradiation with the possibility now to ‘see’ the structure of the generated defects with more details and for certain samples even to count the number of sputtered atoms.
The Nanowerk article includes a link to a video explaining their work. The research has been published:
Physical Review B abstract
If you wish to read the entire research publication without purchasing a PDF from the journal, a preprint is available here.