Fig. 3.

Optical properties and dimension of the carbon dots from seeds of Ocimum basilicum. a) Macroscopic fluorescent development of the basil seed solution during sulfuric acid-induced carbonization reactions observed under UV projection (λ_ex = 312 nm). b) The UV-Vis absorption spectrum (black line) of the carbonized carbon dots from basil seed polysaccharides and the corresponding photoluminescence spectra: Red (λ_ex = 320 nm), orange (λ_ex = 360 nm), green (λ_ex = 400 nm), blue (λ_ex = 440 nm), purple (λ_ex = 480 nm), pink (λ_ex = 520 nm) c) HPLC chromatogram of the ethanol extracted carbon dot products from basil seeds. The highlighted peak was further collected for TEM analysis. d) Characterization of the purified carbon dots by TEM. e) Statistical analysis of the size distribution of the carbon dots shown in the TEM image.