An abnormal non-incubation effect in femtosecond laser processing of freestanding reduced graphene oxide paper

Femtosecond laser ablation of freestanding reduced graphene oxide (rGO) paper and its mechanisms were investigated. An abnormal phenomenon was discovered: the ablated area remained unchanged for the rGO paper with an increasing number of pulses, which was found to be a general feature for a large range of laser fluences. We also studied femtosecond laser ablation of graphene oxide paper and highly oriented pyrolytic graphite film for comparison. Experimental results indicated that the abnormal phenomenon was unique to the rGO paper. As revealed by a combination of SEM, TEM, XRD and Raman techniques, femtosecond laser nonthermal ablation through rolling up of rGO nanoflakes, induced by the distinctive multi-level layer-by-layer structures and the ultrafast energy relaxation of the rGO paper, were considered to be responsible for the non-incubation effect. (paper)