Figure 3. Photo-excited lattice dynamics below T_s.

(a) Temporal evolution of the line cut through the split Bragg peak at T_s>T>T_N at an absorbed pump fluence of 2.9 mJ cm⁻². The inset depicts the line cut on the area detector. (b) Diffraction peak profiles along the line cut at selected delay times. No changes are observed in peak position and width. (c) Subtraction of the averaged line cuts before time zero (Δt=−0.5 to 0 ps) reveals a photo-excited periodic intensity modulation of both orthorhombic domains for positive time delays.