Measurements of vibrational predissociation of SF6 clusters are discussed and compared with theoretical spectra. Attention is given to the line-shape and saturation behaviour as influenced by spatial averaging effects. Also isotopic dimers are considered. Hyperfine-structure measurements of H2–H2, H2–Ne, H2–Ar and H2–Kr dimers are dealt with, and information from these results concerning the intermolecular potentials is discussed.