HRTEM and MD re-examine atomic suspended chains

Publicado em 03/01/2011 – 01/03/2011

Since the discovery of gold LACs, different groups have observed the existence of significantly long interatomic Au–Au distances, 3.6–5.0 Å, in comparison with 2.9 Å in bulk gold.

Controversial topic

The origin of these long interatomic distances has been highly controversial, being attributed to the existence of light impurity atoms (contaminants) inserted between gold atoms, as illustrated above for the case of a hydrogen atom.

Light atoms, in general, do not produce enough image contrast to be discernible in microscopy experiments, even in high resolution transmission electron microscopy (HRTEM).

Puzzle solved?

New HRTEM experiments performed at room and liquid nitrogen temperatures, at the Brazilian Synchrotron Facility (LNLS), combined with ab initio quantum molecular dynamics (MD) simulations, have generated new data suggesting that carbon, produced by the decomposition of hydrocarbon molecules and adsorbed on the nanowires, is a more plausible impurity to explain the long bonds observed in gold LACs. These new data seem to settle a question that has been hotly debated in the literature for almost a decade.

The researchers presented their work in the journal Nanotechnology.

About the author

Maureen J Lagos and Pedro A S Autreto are graduate students at the State University of Campinas, Brazil. Sergio B Legoas is a professor at the Federal University of Roraima, Brazil. Fernando Sato is a professor at the Federal University of Minas Gerais, Brazil. Varlei Rodrigues, Daniel Ugarte and Douglas S Galvao are professors at the State University of Campinas.