Fig. 4
Theoretical fitting of the pump-induced THz spectra. a, b The fitting of Δσ1(ω) and Δε1(ω) for 248 meV (5 μm) photoexcitation with fluence 12 μJ cm−2 at T = 5 K and pump-probe delay Δtpp = 1 ps. The experimental results (red dots) are fitted very well by the THz model from Eq. 1 (cyan lines), which consists of three individual components, i.e., the Dirac surface state (green-dashed lines), bulk state (blue-dashed lines), and optical phonon mode (pink-dashed lines). The fitting results for c, d Δtpp = 9.4 ps and e, f Δtpp = 15.4 ps are plotted in the same manner as a, b
