Raman spectra of diamondlike amorphous carbon films

Abstract

Raman spectra of diamondlike amorphous carbon (a‐C) films prepared under atmosphere with various hydrogen gas content have been measured as a function of excitation wavelength. The Raman spectral profiles vary with excitation wavelength depending on electronic absorption spectra associated with π‐π* electronic transitions. Dependence of Raman spectra on excitation wavelength is interpreted in terms of π‐π* resonant Raman scattering from aromatic rings with various sizes rather than polyene chains. The relative intensity of a 1400 cm⁻¹ band against a 1530 cm⁻¹ band is found to decrease with an increase of sp³ content in a‐C films. It is shown that the relative intensity can be used as a parameter for sp³ content.