Characterization of high temperature conductive graphite surfaces irradiated with femtosecond laser pulses

In this study high temperature conductive graphite surfaces irradiated with megahertz pulse repetition rate femtosecond laser pulses under ambient condition were characterized using electron microscopy and spectroscopy techniques. Scanning electron microscopy analysis of the treated surface shows formation of self assembled weblike nanofibrous structure in and around the laser irradiated spots. Further transmission electron microscopy investigation revealed that this structure was formed due to aggregation of graphite nanoparticles. In addition the broadening of microraman peaks at 1340 and 1580 cm−1 of the laser irradiated sample was due to confinement of optical phonons in graphite nanoparticles. X-ray photoelectron spectroscopy analysis shows a marginal increase of sp2 and sp3 species with laser treated samples as compared to that of untreated samples. The results show that femtosecond laser treatment is rather a simple technique for the direct synthesis graphite nanostructures without significant changes in their chemistry as compared to the bulk.

► Weblike nanoparticles aggregate was generated on graphite surfaces due to irradiation of MHz repetition rate femtosecond laser pulses. ► Nanoparticles were formed by nucleation and condensation of vapor in the plasma plume. ► Microraman study shows that the graphite nanoparticles in the fibrous structure were amorphous. ► X-ray photoelectron spectroscopy analysis shows no significant chemical changes in nanoparticles aggregate as compared to bulk.