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 contribu te importantly. Infrared spectroscopy of weakly bound trimers provides direct insight into the structural and dynamical implications of thes e three-body forces. This is illustrated for the homologous series (HF )(3) - Ar(HF)(2) - Ar2HF - Ar-3, which covers a wide range of intermol ecular interaction mechanisms such as hydrogen bonding, electrostatics , polarization, dispersion, and Pauli exclusion.