3Departamento de Física, Universidad de los Andes, Mérida, Venezuela.

Diamond-Like Carbon (DLC) thin films were deposited on stainless steel and silicon by a r.f. (13.56MHz) magnetron sputtering technique. A carbon target (99.999%) and a gas mixture of Ar/CH₄ were used. During the deposition process the plasma discharge was monitored by Optical Emission Spectroscopy (OES) in order to analyze the state of the chemical species present in the plasma. The films were characterized by Raman Spectroscopy and by Reflection Absorption and Transmission Infrared Spectroscopy. The morphology of the deposited layers was analyzed by Scanning Electron Microscopy (SEM). The Raman analysis confirms the formation of diamond like thin films. The relationship between hte intensity of the diamond and graphite peaks (ID/IG) depends on the percentage of CH₄ in the gas mixture. Optical Emission Spectroscopy shows that, besides of the atomic hydrogen peaks (Ha , Hb , Hg ), emission spectra are dominated by neutral CH species and the most intense peak in the spectra corresponds to CH(A^{2D ®} X^2P at 431.5 nm) which is supposed to be the precursor species in the diamond-like films. On the other hand in the Transmission Infrared Spectroscopy analysis were observed the sp³ CH₂ symmetric and asymmetry stretching peaks at 2850 and 2920 cm^-1, and the sp³ CH₃ symmetric and asymmetric at 2870 and 2960 cm^-1. These peaks have been observed in diamond deposited at very high CH₄ concentrations and also in diamond-like carbon films. *Work supported by the Spanish Program for Science and Technology Development (CYTED). Project VIII.74 "Production and characterization of Hard Coatings".