Figure 9: Experimental and theoretical intensity transients. (a) Lattice temperature derived from diffraction using (1) and (3), for different polarizations, along  (blue dots) and  (red dots), in optimally doped Bi2212. From the three-temperature model described in the text, we obtain that for // (, red solid line) and for // (, blue solid line). The electronic (, dashed lines) and hot-phonon (, solid lines) temperatures are also displayed. (b) Derivatives of the (00) diffraction intensity derived from Figure 2(a) for different polarizations. (c) Derivatives of the simulated lattice temperature within the three-temperature model, for different λ with a fixed anharmonic coupling time τ a = 2.8 ps (also shown in (b)) and for different τ a with a fixed λ = 0.26 (inset). The clear shift of the minimum position is only observed when λ is varied (black dotted lines). (d) Three-temperature model analysis for underdoped Bi2212. (e) Three-temperature model analysis for Bi2223.