Fluorescent carbon quantum dots formed from glucose solution by microplasma treatment

Carbon quantum dots (CQDs) were synthesized of glucose solution by microplasma treatment at atmospheric pressure and room temperature. The spectral-kinetic properties of the synthesized CQDs were studied use of MicroTime 200 confocal scanning luminescence microscope. СQDs have a wide emission spectrum in 400–750 nm area when excited by light with wavelength in the 375–530 nm range. CQD exhibit a bright radiation in the blue range. The concentration of quantum dots was controlled by varying the time of microplasma treatment of glucose solution. The time-resolved fluorescence decay curve was measured by the time-correlated single photon counting (TCSPC) method. Studies of luminescence kinetics revealed three exponential components with decay time constants equal to 0.65, 2.2, and 6.2 ns. The formation of these components is presumably associated with the quantum confinement effect and with presence of different functional groups between which quantum transitions take place.