Pyrazines with terminal donor groups for third-order nonlinear optics: effect of graphene oxide on nonlinear absorption

We report nonlinear optical (NLO) investigations of few pyrazines with terminal donor groups and the influence of graphene oxide (GO) on their nonlinear absorption (NLA) under the nanosecond (ns) pulse excitation. We have used Z-scan and Degenerate Four-Wave Mixing (DFWM) techniques for the NLO investigations and a Q switched Nd:YAG laser (532 nm, 7 ns, 10 Hz) was used as the source of excitation. Modified Hummers method was used for synthesizing GO. A significant quenching in the fluorescence intensity of the pyrazine derivatives was observed when incorporating GO and it suggests the interaction between GO and pyrazine moieties through electron/energy transfer. The pyrazines/GO composites showed strong NLA and it is better than that of the parent compounds. The mechanism behind the NLA is found to be two-photon absorption (TPA) along with excited-state absorption (ESA) and the significant enhancement in the NLA activity of composites can be attributed to the photo induced electron and/or energy transfer between the GO and pyrazine moieties. (author)