The pH dependence of the total fluorescence of graphite oxide.

Graphite oxide was characterized by pH dependent excitation-emission matrices from 300 to 500 nm in excitation and from 320 to 600 nm in emission which reveal the presence of two pH steps. These are assigned to the presence of carboxy groups and phenolic hydroxy groups, respectively. Fluorescence is strongest at 470 nm excitation and 555 nm emission. The fluorescence intensity is a function of pH but not of temperature, and is not quenched by oxygen.