Spatially resolved nanostructural transformation in graphite under femtosecond laser irradiation

- Polycrystalline graphite was irradiated with a high power fs (IR) laser.
- Presence of a diamond peak was detected by synchrotron XRD.
- XPS and Raman showed in-depth sp3% increase at tens of nm below the surface.
- sp3% is increasing with laser power density but it is independent of photon absorption rate.
- Graphite crystallite size locally increase at tens of nanometers below the irradiated spots.