Field ion microscope

FIM like field-emission microscopy (FEM) consists of a sharp sample tip and a fluorescent screen (now replaced by a multichannel plate) as the key elements.

The imaging atoms then lose their kinetic energy performing a series of hops and accommodate to the tip temperature.

For these reasons, refractory metals with high melting temperature (e.g. W, Mo, Pt, Ir) are conventional objects for FIM experiments.

The final preparation procedure involves the in situ removal of these asperities by field evaporation just by raising the tip voltage.

The problems studied include adsorption-desorption phenomena, surface diffusion of adatoms and clusters, adatom-adatom interactions, step motion, equilibrium crystal shape, etc.

However, there is the possibility of the results being affected by the limited surface area (i.e. edge effects) and by the presence of large electric field.

In a recent study from Günther Rupprechter laboratory examined a rhodium nanocrystal surface using field emission microscopy consisting of different nanometer-sized nanofacets as a model of a compartmentalized reaction nanosystem.

The transitions between different modes were caused by variations of the hydrogen pressure modifying the strength of diffusive coupling between individual nanofacets.