New Applications of the Parity Law to Secondary Ion Emission.

First, it is shown that the results of recent experiments confirm the idea that the emission intensities for the SIMS molecular ions (or for ions produced by other techniques discussed in the paper) reflect the physical properties of the emitted clusters and that they are little influenced by the initial arrangement of atoms at the surface. Using this conclusion,, three recent experimental results on Au//n** plus , I//n** plus and X//nY//p** plus ions (where X is a halogen and Y an alcalin atom) showing that they satisfy the parity rule which predicts that the intensities are the largest when the number of valence electrons in the neutral corresponding cluster is odd.