Basics of liquid metal ion sources

A practical application coming out of field ion emission is the liquid metal ion source. Ion sources of a wide variety of chemical elements, most of them low melting point metals, can be produced by using either liquid metals131,132 or liquid alloys.133 The idea of extracting charged droplets out of liquid by application of an electrostatic field is perhaps older than field ion microscopy. But the development of liquid metal ion sources from liquid capillaries, from slit shaped emitter modules and from wetted field emission tips, etc., as well as the understanding of the mechanisms of ion formation in terms of field evaporation and field ionization theories, 

secondary ion mass spectroscopy with sub- p,m spatial resolution for chemical analysis of sub-p,m structures,139 

The mechanisms of ion formation are usually studied with measurements of mass separated ion energy distributions using a magnetic sector mass spectrometer.144,145 For a liquid metal ion source, both atomic ions and cluster ions of all sizes are emitted. If the total ion current is large, neutral atoms and small droplets may also be emitted. There is little question that most of the atomic ions in a liquid metal ion source at low 

In the 1960s emission of charged droplets was of primary interest because of the possible use in spacecraft propulsion, although for efficiency ions should be the preferred emitted species for propulsion purposes. There is a renewed interest in this phenomenon because of 

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