Effect of laser treatment on the structure and spectral-luminescent properties of graphene dots

The structure and optical properties of nanodots based on graphene oxide (GO) obtained by ablation by laser radiation with different wavelengths were studied. It was shown that after laser ablation, the average lateral size of GO sheets decreases from 820 $\pm$ 120 nm to 204 $\pm$ 40 nm and 105 $\pm$ 23 nm for samples prepared at $\lambda_{\mathrm{gen}}$ = 355 and 532 nm, respectively. In this case, a change in the intensities of the 2D and G bands was observed, which indicates a decrease in the number of layers in the GO sheets. The optical density of GO dispersions and the intensity of fluorescence depend on the ablation conditions. After ablation, the optical density of GO increased by $\sim$ 13% for samples obtained at $\lambda_{\mathrm{gen}}$ = 355 nm and by 20% for $\lambda_{\mathrm{gen}}$ = 532 nm. The fluorescence intensity of GO ablated at $\lambda_{\mathrm{gen}}$ = 532 nm increased by 57% relative to the value registered for GO before ablation. For 355 nm, the fluorescence intensity was changed by 7%.