Persistent spectral hole burning was performed on the 7F0–5D1 transition of Sm2 + in thin films of SrFCl. Depending on the substrate and the growth conditions, a total hole depth between 47% and 70% was reached. The holes were Lorentzians of width 4(±0.3) cm – 1. The time evolution of the hole depth was studied. It is described by two exponentials: a short time decay (t1 = 0.37 days) and a long time decay (t2 = 20.4 days) with a 20% infinite time limit. One- and two-photon burning mechanisms act.