Reactivity of soft amorphous hydrogenated carbon films in ambient atmosphere

Thermally induced decomposition of soft amorphous hydrocarbon films was investigated by thermal effusion spectroscopy. Released species were detected by a sensitive mass spectrometer. Soft films exhibit a desorption maximum at T ≈ 760 K while hard films have their maximum at T ≈ 875 K. We found a significant reactivity of soft layers towards air and in particular towards humidity in the air. After three month exposure to ambient atmosphere, thermal effusion spectra are significantly different. Water and carbon dioxide peaks increase with exposure time whereas the contributions from hydrocarbons decrease.