Lithium clusters were prepared by evaporating lithium in argon at a pressure of 10-4-10-2 Torr and the mass numbers of these clusters containing up to 15 atoms and their relative abundances were measured by a quadrupole mass analyzer. In good vacuum lithium was detected as single, electrically neutral atoms. When argon was present, clusters composed of an even number of atoms were always detected. Li3 and Li5 were never detected. In the range Li7 to Li15 of clusters composed of an odd number of atoms were detected in smaller amounts than the case for neighbouring clusters containing an even number of atoms.
A few experimental studies by means of various methods concerning clusters are reviewed briefly.
