Ionization of liquid metals, gallium

Field ionization of a liquid metal, such as Ga or In, has attracted considerable interest since it could become a source of strong focused ion emission. We have studied this phenomenon using the improved magnetic‐sector atom‐probe field ion microscope. The energy distributions of field ionization of Ga and critical energy deficits are measured as a function of surface temperature and electric field. The field ionization of Ga can be divided into a low and a high emission region. In the low emission region Ga+ ions are emitted at a field of approximately 0.5 V/A when the emitter is heated to approximately 600 °C. The intensity of this Ga+ emission is sufficient to yield a desorption image of the emitter surface. This implies that the ion flux is ∠103 ions/atomic site/second. When the emitter is kept at low tempertures (78 K) the emission is predominately Ga++. In both cases the ions display a sharp energy distribution (?1.5 eV FWHM) and a small energy deficit (?2.1 eV). In the high emission regime Ga++ ion...