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## C. Superconducting response in SmFeAsO 0 . 8 F 0 . 2 

For easier separation of component C associated with the superconducting response we use the fact that com- ponents A and B are temperature independent in the superconducting state. We therefore extract component C by subtracting the average of transients measured at 55 and 65 K from transients measured below 55 K. The subtracted transients clearly show a two-step decay with a finite rise time and are excellently fit by equation (4) as shown in Fig. 10. 

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In the spirit of the Rotwarf-Taylor model 27 we asso- ciate the rise time with establishment of the thermal quasi-equilibrium between the photo-excited quasiparti- cles and high frequency ( ℏ ω > 2Δ$_{SC}$ ) phonons. The shorter relaxation time is associated with establishment of the local thermal equilibrium between all degrees of freedom, while the longer relaxation time is due to en- ergy escape out of the probed volume. This is supported by increased relative amplitude of the long decay with respect to the total amplitude at higher F . Neither the rise time nor the relaxation times (see Fig. 

11) show any temperature dependence within experimen- tal error, while only τ$_{rC}$ $^{shows dependence on}$F and ℏ ω$_{P}$ . τ$_{rC}$ is always faster at ℏ ω$_{P}$ = 1 . 55 eV and shows much weaker F -dependence than at ℏ ω$_{P}$ = 3 . 1 eV, where it in- creases from 0.3 ps at F = 3 µ J/cm 2 to 0.6 ps at F = 15 µ J/cm $^{2}$. While an increase of τ$_{rC}$ with increasing ℏ ω$_{P}$ is expected due to the photo-excitation being farther away from ϵ$_{F}$ an increasing F -dependence with increasing ℏ ω$_{P}$ is not completely understood. 

In Fig. 12 we plot F -dependence of the component C amplitude, A$_{SC}$ . Similarly as in the cuprates 31 the response saturates with increasing F indicating a com- plete destruction of the superconducting state in the ex- cited volume. By taking into account the effects of in- homogeneous excitation due to finite penetration depths and beam diameters 31 we determine the threshold ex- 

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ternal fluence, F $_{T}$, at which the superconductivity is destroyed in the most excited spot of the pump beam. From F T we calculate, using optical penetration depths, λ$_{op}$ , and reflectivities, R , of LaAsFeO$_{1}$ − x F x , 44 the en- ergy density, U$_{p}$ , required to completely destroy the su- perconducting state: U$_{p}$ / k$_{B}$ = F$_{T}$ (1 − R ) / λ$_{op}$k$_{B}$ = 2 . 2 K/Fe ( U$_{p}$ = 18 J/mol) at ℏ ω$_{P}$ = 3 . 1 eV and U$_{p}$ / k$_{B}$ = 1 . 5 K/Fe ( U$_{p}$ = 12 J/mol) at ℏ ω$_{P}$ = 1 . 55 eV. The average value U$_{p}$ / k$_{B}$ = 1 . 8 K/Fe is slightly smaller than the values ob- served in La$_{1}$ − x Sr x CuO$_{4}$. 31 If we assume that the ther- modynamic superconducting condensation energy, U$_{c}$ , in SmFeAsO$_{0}$ . $_{8}$F$_{0}$ . 2 is similar to La$_{1}$ − x Sr x CuO$_{4}$ due to simi- lar magnitudes of T$_{c}$ we obtain U$_{p}$ / U$_{c}$ ≫ 1 indicating that a significant amount of excitation energy is transferred to the bath on a timescale of ∼ 0 . 3 ps. If all degrees of freedom would absorb U$_{p}$ the resulting temperature rise would be 11K based on the published heat capacity, c$_{p}$ , data $^{45}$. Contrary to the cuprates c$_{p}$ is dominated by Sm spins 45,46 below ∼ 12 K so it is not possible to determine whether the excess U$_{p}$ is absorbed in the Sm-spin or in the phonon subsystem. 

We fit the temperature dependence of the reflectivity change upon complete destruction of the superconduct- ing state shown in Fig. 11 (d) by the high-frequency limit 

