We have investigated the acetylene-plasma deposition of amorphous carbon film using “in-situ”, “real-time” infrared absorption spectroscopy in the multiple internal reflection geometry (MIR-IRAS). We showed that sp-hydrocarbons are dominant species at the initial stages of deposition, while sp3-hydrocarbon components increase their densities with film growth. IRAS data obtained for the deposited amorphous carbon film exposed to deuterium plasma showed that the density of the sp-hydrocarbon components is relatively high in the vicinity of the film surface. On the basis of the present experimental results, we suggest that the sp-hydrocarbons are transformed into the sp2-, sp3-hydrocarbon components at the film surface through the addition reaction.
