²⁵²CF-Plasma Desorption Mass Spectra of Very Large Clusters

Abstract

The ²⁵²Cf plasma desorption mass spectra of gold clusters of molecular weight ca 17000 a.m.u are reported and explained in terms of structures involving vertex sharing icosahedra. The spectra seen depend on the surface from which the ions are desorbed. From a gold surface peaks are seen due to clusters of stoichiometry Au₂₅(PPh₃)₁₂Cl₆; Au₄₆(PPh₃)₁₂Cl₆ and Au₆₇(PPh₃)₁₄Cl₈. On a nitrocellulose surface peaks are seen up to m/z 56000. A condensation of clusters appears to be occurring and a mechanism by which this condensation takes place is proposed.