Growth and treatment of hydrogenated amorphous carbon nanoparticles in a low‐pressure plasma
A parallel ‐ plate, low ‐ pressure plasma for fundamental nanodusty plasma re-
search is used to grow hydrogenated amorphous carbon nanoparticles using
an argon ‐ acetylene gas mixture. The particles stay confined in the volume of
the argon plasma after turning off the C H 2 2 gas flow and the effects of pro-
longed treatment with noble gas (Ar) and reactive gas mixtures (Ar/ H 2, Ar/ D 2,
or Ar/ O 2) are investigated using in situ infrared absorption spectroscopy.
Additionally, ex situ scanning electron microscopy imaging of extracted na-
noparticles is used to analyze their size and surface morphology. In 45 min of
argon treatment, a size increase of about 50% is seen together with a decrease
in sp CH x
bonds and an increase in C ═ O bonds, indicating incorporation of
oxygen from gas impurities into the particle material. All reactive gas mixtures
lead to the expected etching of the nanoparticle material without any ex-
change reactions between gas ‐
phase deuterium and surface ‐
bonded hydrogen atoms.
These results are important for
in situ studies of nanoparticle
clouds such as dust density
wave diagnostics, but they also
provide fundamental informa-
tion about plasma interaction
with a ‐ C:H material.