Deuteron Magnetic Resonance and Infrared Absorption Studies of Structure and Dynamics in Amorphous Hydrogenated Carbon and Carbon Nitride

Abstract

ABSTRACTDeuteron magnetic resonance (DMR) and infrared absorption spectra have been measured in amorphous hydrogenated carbon (a-C:H and a-C:D,H) and amorphous hydrogenated carbon nitride (a-CN:D,H) films plasma-deposited onto room-temperature substrates from feedstock mixtures of CH4, N2, and D2. DMR spectra and transient magnetization recoveries were measured between room temperature and 4 K. Recoveries are dominated by magnetization transport under extreme inhomogeneity. Methyl rotors CDx H3-x freeze out below 77 K. From the infrared absorption spectra, NH2, CHx, double bonded C-C, and triple bonded C-N stretching modes are observed. As a function of increasing nitrogen concentrations, the NH2 and C-N intensities dramatically increase while the CHx and C-C intensities decrease. In films where the ratio of nitrogen to carbon plus nitrogen is greater than 25%, the absorption spectra are dominated by NH2 stretching and bending modes; in contrast, the DMR spectra show many CDxHy configurations and a broader NDxHy structure. Proton NMR shows significant hydrogen clustering in a-CN:D,H.