“…In addition, to corroborate their chemical composition, Figure 2 shows the representative FT-IR spectrum of each kind of material synthesized. The spectrum for RF xerogel (see Figure 2 a) showed the characteristic bands for these organic materials, which can be assigned as follows: the methylene ether bridges C-O-C (474, 1090, 1217 and 1298 cm −1 ), aliphatic C-H bonds (1459 cm −1 ), aromatic C-H bonds (1511 cm −1 ), aromatic ring stretching vibrations C=C (1610 cm −1 ), C-H stretching vibrations (2930 cm −1 ) and -OH stretching vibrations (3000–3600 cm −1 ) [ 25 , 34 , 35 ]. On the other hand, bands in the Si spectrum (see Figure 2 d) corresponded to those of a silica material synthesized from TEOS: the asymmetric stretching vibration and bending vibrations of Si-O-Si (470, 796 and 1090 cm −1 ), Si-OH bonds (970 and 3400 cm −1 ) and CH2 stretch (1600 cm −1 ) [ 20 , 25 , 28 ].…”