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.