Summary

A comparative research of the absorption and fluorescent properties of carbon dots (CDs) obtained by microwave synthesis from citric acid and L-cysteine has been carried out. The sizes of synthesized CDs differ from 2 to eight nm, with a mean dimension of three.5 nm. FTIR spectra affirm the presence of oxygen-containing (-OH and С=О), in addition to -CN, -NH and -SH teams. It has been proven that for L-cysteine-doped CDs, the absorption spectrum moreover displays a band with a most at 350 nm, whereas for undoped CDs it was absent. For all investigated CDs, improve within the excitation wavelength led to the “crimson” shift of the fluorescence spectrum. The utmost fluorescence depth is noticed upon excitation at 350 nm. The very best fluorescence quantum yield (68%) was obtained for CDs with a citric acid and L-cysteine ratio of 1:0.5 and 1:1. The fluorescence lifetime of doped CDs additionally will increase from 6.6 ns to 7.8 ns. It’s proven that doping of CDs with N- and S-containing teams makes it potential to regulate their absorption and fluorescent properties.