Fig. 6.

(A) Chemical equation for dimerization of acetic acid; (B) Graphical representation of limitations of derivative FTIR spectroscopy to unfold overlapped signals (a₁, a₂ and a₃ are critic points: (i) a₁ and a₂ can be identified by derivative FTIR spectroscopy whereas into (ii) a₂ cannot be identified as a critic points because a₁ > a₃ > a₂; (C) illustration of effect of capacity of FEDS technique to separate the overlapped signals and ease the identification of no-evident signals into FTIR spectra of water, acetic acid and their mixtures.