Increment of the fluence ΔΦ of both the NWs, and the planar rate over the increment of evaporated incident fluence ΔΦ
, as a function of the evaporated fluence Φ
. In particular, in the case of the NW, ΔΦNW has been calculated as the increment of the areal densities of atoms contributing to the NW growth. This ratio represents the axial growth rate of the NW derived with respect to the evaporated fluence.