The behavior of tetrafluoromethane microwave plasma (2% argon included)
has been studied by
emission spectroscopy during the treatment of hexatriacontane, a model
for high density polyethylene.
The evolution of the densities of F* atoms, and CF, CF*
radicals has been followed by using the
actinometric technique with 2% argon added to the gas.
The surface properties, such as surface energy and
surface roughness were correlated to the emission intensity
of reactives species in the plasma gas phase.
We found that the evolution of the fluorinated species
emissions in the plasma gas phase can be a direct
indication of the surface modifications by the plasma.
A mild exposure to the plasma can result in a great
decrease of surface energy corresponding to the fluorination.
The surface roughness only changes under
drastic plasma conditions. Threshold ionization mass
spectroscopy is applied to detect the fluorine atoms
Time resolved measurements in pulsed plasma,
give access to the decay rate of F atoms concentration in
the afterglow, and to their sticking coefficient on different surfaces.
The influences of the discharge
parameters and of the surfaces (metal, silicon or hexatriacontane) in contact with the plasma are
investigated. The results show that the plasma generated ions and/or UV radiations highly enhance the
reactivity of the F atoms on polymer surface.