We study the 514 and 244 nm Raman spectra of a wide variety of hydrogenated amorphous carbons (a-C:H). The hydrogen content can be estimated from the slope of the photoluminescence background (PL) of the spectra measured at 514.5 nm. Generally, the evolution of the sp and sp phases is not independent for as-deposited a-C:H samples. This, in principle, allows us to derive their structural and op...
