Molecules made of only two Helium atoms (Dimers, He2) and three atoms (Trimers, He3) are extremely fragile, floppy and diffuse quantum objects. The Helium dimer has the by far longest and weakest bond ever observed. It spreads over 100 times the atomic radius. For the trimer an excited halo state, a so called Efimov state, is predicted but not yet found experimentally. We study the fascinating quantum nature of the Helium dimer and trimer experimentally: We ionize them with synchrotron radiation, short laser pulses and hit them with protons and relativistic Uranium ions.
Further information about measurements done so far can be found here: