The Raman spectrum of graphite measured with TRR setup shown in Fig. 2(a) has two main features: the G peak at ~1580 cm−1 and the 2D peak at ~2700 cm−1 (Fig. 2(b)). The G peak is the zone center E2g phonon. The 2D peak is due to the two-phonon scattering at K points called double resonance303132. These peaks measured by the 395 nm ultrafast probe pulse sit on a luminescence background and have large linewidths due to the finite bandwidth of the pulse. The absence of the defect-induced D peak (~1350 cm−1) indicates good quality of our sample. Figure 2(c) displays the anti-Stokes spectra at various delay times. We fit the phonon spectrum at each time delay with a Gaussian (Fig. 2(d)) and then extracted the integrated intensity as a function of time (Fig. 2(e) blue dots and inset).