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The tip shape of a Au-Si liquid-metal ion source in terms of its dependence on the total ion emission current has been investigated in situ in the Halle 1 MeV electron microscope. Within the emission current range 7-90 mu A there is a linear dependence of the cone half-angle a and the length I of the jet-like protrusion on the increased emission current. The jet-like protrusion at the Taylor cone vertex was not so pronounced as has been observed in the cases of elementary liquid-metal ion sources. No spatial shifts of the Taylor cone are seen during the experiments. In contrast to elementary liquid-metal ion sources, there is no indication of 'Faraday droplets' being emitted from the surroundings of the Taylor cone.

Lead liquid metal ion sources (LMISs) were operated using a special specimen holder in situ in a 1 MeV TEM. The dynamics of the tip shape have been observed as a function of the ion emission current. At currents there was a jet-like protrusion on the vertex of the Taylor cone. Linear dependences were found for the decrease of the cone half-angle and the increase of the jet length l as functions of increase in ion emission current. Microdroplet emission was observed at the shank of the Taylor cone over time intervals of 0.1 s and more. The diameter of these microdroplets varied between 40 and 340 nm. This work has improved our understanding of the ion and microdroplet emission processes from the Pb LMIS.

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