Figure 1

Time evolution of optical pump-TTDS probe experiments.
(a) Frequency of the normalized transmission as a function of time up to 8 ps following excitation at 1.57 eV. Regular modulation of the amplitude on top of the peak at 1.8 THz is apparent. (b) Frequency as a function of time following excitation at 3.14 eV, across the Mott gap, which does not show oscillations. (c/d) Overhead views of (a/b), with the colors representing the same amplitude of the normalized transmittance. (e) Calculated and experimental phonon DOS. The dispersion curves giving the DOS are in Supplementary Fig. S1 online.