Pendant benzene in hydrogenated diamond-like carbon

We show that nearly all of the infrared absorption associated with sp2 coordination in diamond-like carbon deposited from benzene plasma is due to pendant (mono-substituted) benzene. Because these pendant groups have little effect on the optical and mechanical properties of the film, which are determined by the connected covalent network to which they attach, they obscure the connection between those properties and the sp3 /sp2 bonding ratio in diamond-like carbon.