“…This illustrates very well that the lowest energy conformer 4 + 0 of Li + (H 2 O) 4 cannot be completely ruled out from the distribution of conformers formed in the experiment, as nicely shown by the collisions. 29 Figure 3 now presents the IR-PD spectrum of Li + (H 2 O) 3 Ar recorded through the Ar loss channel (bottom) together with the dynamical IR spectra computed at 50 K for the three lower energy conformers of Li + (H 2 O) 3 , namely 3 + 0, 2 + 2, and 2 + 1, respectively, second, third, and fourth traces in Figure 3. The 2 + 2 and 2 + 1 conformers were found to be quasi isoenergetic (Table S1, Supporting Information), separated by a barrier of about 4.0 kJ/mol (free energy barrier from metadynamics simulations, see Figure S2 in the Supporting Information), and about 30 kJ/mol higher in energy than the 3 + 0 lowest energy conformer (Table S1, Supporting Information).…”