Fig. 4: Electronic structure response to the shear mode excitation.

a Close-ups of the ARPES intensity map near E_F at Δt = 120 fs (top) and the corresponding 0.23 THz Fourier map (bottom). The data is overlaid with experimental band dispersions from ref. ¹¹. Surface bands were omitted for the sake of clarity. Crosses mark positions of ROI A–D and A′. The Fourier map was generated from ARPES intensity maps that were binned over regions of 23 meV × 0.01 Å⁻¹. b Schematic illustration of the atomic motion upon excitation of the interlayer shear mode³¹. c Calculated bulk band structure along the Γ–X direction. d PE intensity transients of ROI A–E. The transients of ROI A–C (top graph) can barely be discerned and are all displayed in red. The size of the integration area used to generate the transients is indicated by the gray-shaded box in the ARPES data shown in a. e Peak shift analysis of ROI A′, C, and reference region E marked in Fig. 3a. All transients in d and e are background-corrected (Supplementary Note 3). The black lines in the top graphs of d and e are fits of a damped sinusoidal function.