Raman scattering of thin laser-deposited amorphous-carbon films reveals significant changes in lower and intermediate spectral regions with respect to rf-sputtered, predominantly threefold a-C. The form of the spectrum differs, however, from the expected spectrum for fourfold, diamondlike a-C. It is suggested that mixed bonds between threefold and fourfold sites in diamondlike materials modify the lower-frequency bond-bending modes and Raman scattering.

• Received 25 January 1993

DOI:https://doi.org/10.1103/PhysRevB.47.10931