Study of influence of external plasma parameters on plasma polymerised films prepared from organic molecules (acrylic acid, allyl alcohol, allyl amine) using XPS and NEXAFS

Plasma polymerised films of acrylic acid, allyl alcohol and allyl amine were prepared and studied by XPS (X-ray photoelectron spectroscopy) and XAS (X-ray absorption spectroscopy). The influence of external plasma parameters on certain chemical aspects of the films was investigated. The use of XPS and NEXAFS (near edge X-ray absorption fine structure) as complimentary tools in the surface characterisation of thin films has been highlighted. Certain chemical aspects of the plasma polymerised films such as presence of ROCO in the case of plasma polymerised acrylic acid films, presence of RCO and RC–OR bonds in case of plasma polymerised allyl alcohol films and presence of RCN and C≡N in case of plasma polymerised allyl amine films were studied. The concentration of ROCO species was found to decrease with increase in r.f. duty cycle in the case of plasma polymerised acrylic acid films. In case of plasma polymerised allyl alcohol films there is a decrease in the concentration of RCO species and increase in the concentration of RC–OR species at higher pressures, while in the case of plasma polymerised allyl amine films the concentration of RCN and C≡N increases at higher powers, with an increase in C≡N more pronounced at higher powers.