Figure 2: Evidence for an ultrafast time scale.

Transient differential absorption of ultraviolet-irradiated aqueous graphene oxide (GO) dispersions at 400 nm. (a) Titration of the GO concentration dependence of the dynamics, in water, ranging from 0 mg ml⁻¹ to 2 mg ml⁻¹ on a 10 ps time scale. (b) Long time scale dynamics of a 1 mg ml⁻¹ GO dispersion versus pure water. (c) Plot of the residual absorption value in ΔOD versus graphene oxide concentration. The vertical error bars are the standard deviation of the calculated values displayed. Each point represents the average intensity of the last 2 ps (from 8–10 ps), thus the error bars represent the noise level. The horizontal error bars represent an estimated 5% experimental error on the measure of the absolute GO concentration.