July 23, 2015

Make mine a decaf: breakthrough in knowledge of how nanoparticles grow

University of Leicester and CNRS researchers observe how nanoparticles grow when exposed to helium

(July 23, 2015)  A team of researchers from the University of Leicester and France’s G2ELab-CNRS in Grenoble have for the first time observed the growth of free nanoparticles in helium gas in a process similar to the decaffeination of coffee, providing new insights into the structure of nanoparticles.

Nanoparticles have a very large surface area compared with their volume and are often able to react very quickly. This makes them useful as catalysts in chemical reactions and they are often used in sports equipment, clothing and sunscreens.

In a paper published by the Journal of Physical Chemistry Letters and funded by the Royal Society, The Leverhulme Trust, the British Council and CONACYT, the teams from the University of Leicester’s Department of Physics and Astronomy and the CNRS in Grenoble measured how helium ions cluster with neutral helium atoms and grow into nanoparticles.

During the study they examined how helium ions drift through a cell filled with helium atoms. When the pressure of helium was increased the researchers observed a decrease in the mobility of the ions.

Dr Klaus von Haeften from the University of Leicester’s Department of Physics and Astronomy, who has received a Visiting Professorship from the University Joseph Fourier, said: “We concluded that the increased pressure forced more and more helium atoms to bind to the ions gradually, until the clusters grew to nanometre-sized particles. This process continued until the nanoparticles reached the maximum size possible which also depended on the temperature.

journal reference >>