The vDOS spectrum for 10 randomly chosen surface water molecules (including W_A and W_B) before formation of CO₂ (black, thermal equilibrium) and 120 ps after CO+O recombination (blue). The spectrum at t = 120 ps reproduces all features of the equilibrium vDOS, i.e. the system has returned to equilibrium on the 120 ps timescale. The intensities are “populations of modes within a given frequency interval”.