  Atom probe tomography (APT) analysis conditions play a major role in the
composition measurement accuracy. Preferential evaporation, which significantly
biases apparent composition, more than other well-known phenomena in APT, is
strongly connected to those analysis conditions. One way to optimize them, in
order to have the most accurate measurement, is therefore to be able to predict
and then to estimate their influence on the apparent composition. An analytical
model is proposed to quantify the preferential evaporation. This model is
applied to three different alloys: NiCu, FeCrNi and FeCu. The model explains
not only the analysis temperature dependence, as in already existing model, but
also the dependence to the pulse fraction and the pulse frequency. Moreover,
the model can also provide energetic constant directly linked to energy
barrier, required to field evaporate atom from the sample surface. 2
