Fig. 5.

(A) Line FEDS-FTIR plot for water: a₁, a₂, b, and c denote the vibration signals for water molecule; (B) normalized FTIR spectra for water, acetic acid and water-acetic acid at different proportions; (C) identification of water scissor vibration, it was identified as “b” in Fig. 5A, by FEDS for different water-acetic acid mixtures (0.8, 0.4, and 0.1 v/v of water); and (D) calibration fit used to determine the water concentration in a water-acetic acid mixture.