POTENTIAL SURFACES AND DYNAMICS OF WEAKLY-BOUND TRIMERS - PERSPECTIVES FROM HIGH-RESOLUTION IR SPECTROSCOPY

Forces between molecules are dominantly, but not exclusively pairwise additive. For several types of interaction, three-body forces contribute importantly. Infrared spectroscopy of weakly bound trimers provides direct insight into the structural and dynamical implications of these three-body forces. This is illustrated for the homologous series (HF)(3) - Ar(HF)(2) - Ar2HF - Ar-3, which covers a wide range of intermolecular interaction mechanisms such as hydrogen bonding, electrostatics, polarization, dispersion, and Pauli exclusion.