Investigation of a tin liquid metal ion source

A Sn liquid metal ion source was prepared employing a Ni needle to anchor the liquid ion emitter. The main source properties, i.e., the I-V curve, the mass spectra, the energy spread for the main species, as well as the long term source stability were systematically studied. Moreover, a new etching technique for Ni tips has been developed. The mass spectra show a large amount of Sn clusters, apart from the dominant species, Sn+ and Sn++. The source was stable down to 1µA emission current, corresponding to an energy spread for the singly-charged ions of 7 eV. Theoretical arguments strongly suggest that both Sn+ and Sn++ are emitted by direct field-evaporation from the liquid surface.