Spins and microstructure of amorphous carbon

Abstract

Variable frequency EPR measurements between 9 and 285 GHz show that a-C layers with the exception of strongly polymer-like layers present even at the highest frequency a simple, single line EPR spectrum for which exchange interactions are still dominating. The high frequency EPR spectra are characterized by temperature dependent g-factor anisotropies, the numerical value of which varies with the particular samples. From the angular variation, temperature and microwave frequency dependence this g-factor anisotropy is attributed to the influence of demagnetizing fields which at 285 GHz and 4 K are of the order of 100 G for the diamond like layers.