Figure 3

(a) Color-coded 2D time–frequency map of the relative transmittance change in Sb₂Te₃ films upon excitation with fs-laser pulses of 100 fs at 1.55 eV energy and at 0.1 mJ/cm⁻² fluence. (b) Result of the Lorentz fits (blue-total, green-phonon) of the transient linear normalized absorbance peak in the 80 nm Sb₂Te₃ epitaxial film. The total fit curve (blue) also takes into account the satellite peak at 40 cm⁻¹. The peak at 62 cm⁻¹ (E_u) shows both, a transient intensity increases as well as a change of its pumped spectral width Γ_p 15% larger upon 1.55 eV pumping than the unpumped width Γ_u. A broad band offset growth beneath the phonon line (orange lines) indicates the Drude free carrier part of the dielectric function. The absorbance is normalized to the spectra taken at −14 ps delay before time zero.