FTIR measurements are carried out to identify the biomolecules
responsible for the reduction and stabilization of Au NPs. The FTIR
spectra of diluted essential oil and Au colloid are given in Fig. 6a
and b, respectively. The oil has a strong absorption at 2926 cm1
due to C–H stretching vibrations of hydrocarbon. Medium absorption peaks occurred at 1368 cm1 (C–O stretching vibrations of
carboxylic acid), 1448 cm1 (C–O–H vibrations of carboxylic acid),
1645 cm1 (aromatic ring) and 1713 cm1 (C@O vibrations of acid)
[13,15,22,31–34]. The medium band at 1368 cm1 due to C–O
stretching of carboxylic acid in Fig. 6a gets shifted to 1324 cm1
in Fig. 6b. The C–O–H vibration of carboxylic acid present in the
oil gave medium band at 1448 cm1 which becomes weak and