Development and experimental application of a gold liquid metal ion source

A liquid metal ion source (LMIS) based upon a gold/germanium eutectic has been developed. The LMIS emits a variety of ions including monatomic gold and gold clusters. Gold ions have been utilised for SIMS analysis of the polypeptide gramicidin and the polymer poly(ethylene-terepthalate) (PET). It has been found that monatomic gold (Au+) increases secondary ion yields up to a factor of four compared to gallium, for both gramicidin and PET. The Au3+ cluster produces a strong non-linear increase in yield over monatomic gold, for both gramicidin and PET. This effect is greatest at high mass, the yield for the gramicidin molecular ion increasing by a factor of over 60. No evidence has been found to suggest increased fragmentation as a result of cluster ion bombardment. The LMIS also exhibits good static SIMS imaging capacity.