On the hydration and hydrolysis of carbon dioxide

► X-ray absorption spectra of the aqueous carbon cycle measured using liquid microjets. ► Carbonate (pH = 12), bicarbonate (pH = 8.5), and carbonic acid/CO2 (pH = 3) were probed. ► Electronic and dynamical simulations reveal the origins of clear spectral differences. ► Defining factors are molecular configuration, bond lengths, and hydration strength. ► Vibronic peaks in CO2 spectra are particularly sensitive to aqueous solvation.