Intermolecular Interactions: van der Waals Molecules

Recent experiments using electron diffraction techniques, optical and infrared spectroscopy and mass spectroscopy have provided convincing evidence for the existence of bound states of gaseous Ar 2 , (H 2 ) 2 , (O 2 ) 2 , (NO) 2 and other simple dimers. The bond strength of these van der Waals molecules is hundreds of times weaker than ordinary chemical bonds. These experimental studies yield information on the structure and stability of van der Waals molecules and can provide new insight into weak intermolecular interactions.