The nπ * lifetimes are also prolonged for a = 3.5 Å, to ∼3 and ∼11 ps for the free tetramer and SAM, respectively. It is in qualitative agreement with Ref. 33. The corresponding ground-state recovery times are ∼7.4 ps and ∼21.7 ps. Thus, we observe that the return to the ground state is delayed in the tightly packed SAM. It is again in qualitative agreement with previous simulations. It is interesting to compare the obtained lifetimes to those reported in the recent study employing exciton model / surface hopping approach, performed for 12 QM azobenzene chromophores. After ππ * excitation, the following lifetimes were obtained: τ ππ * ≈ 0.27 ps and τ nπ * ≈ 3.41 ps. Whereas a direct comparison is not possible since the considered systems are different, we note that the ππ * lifetime of Ref. 46 is much shorter than the ππ * lifetimes in Table . This may originate from the long ππ * lifetime of the monomer obtained here using the simple, three orbital CIS level.