Quantum yield

The relative fluorescence quantum yield of resultant CQDs were evaluated at an excitation wavelength of 320 nm and the following equation was used‏:

Where, r and x reflect the standard reference and the sample of interest respectively, Q is the quantum yield, I is the integrated emission spectra, η is the refractive index of the solvent, and A is the absorbance. In order to avoid self-absorption effect, the absorbance was kept below 0.1 quinine sulfate in 0.1 M H2SO4 because lead to avoid self-absorption effects. Quinine sulfate had known quantum yield of 0.54 that was selected as standard reference‏.