The D and G in the spectra often partially overlap.  It should therefore be preferable to fit them to two Lorentzians, and determine the ratio from the fit.

Hello.

Generally I stand for the height and A for area in the litterature. Other bands are sometimes introduced (D1, 2, 3...). This is the case for raman spectra of soot (Sadezki et al,...). I published a paper this year in Vibrational Spectroscopy where I tried a different approach (using a aC component and a nanocristalline component). In that paper you ll find references concerning different ways to fit. A new way to fit is from a paper of Pascal Puech from last year, but the first autor is Mallet if I remember correctly. Good luck. Regards. Cedric 

Thank you very much for your answers.