The vibrational spectrum of the water dimer: Comparison between anharmonic ab initio calculations and neon matrix infrared data between 14,000 and 90 cm−1

► Observation of the vibrational spectrum of the water dimer from the far infrared to the visible. ► Assignment based on 18O/16O shift and on approximate values of anharmonicity coefficients. ► Calculations in the framework of the second-order perturbation - resonance theory.