3D atom probe assisted by femtosecond laser pulses

The 3DAP allows to image a material in 3D on a nearly atomic scale. It is based on the field evaporation occurring at the surface of a biased tip like shape specimen with an end radius of 50 nm. Surface atoms are removed one by one from the tip by means of fs laser pulses so that the physical process involved in this laser enhanced field evaporation might correspond to the very early stages of the ablation process. This technique makes possible to distinguish between different regimes of material removal such as thermal evaporation or in the case of metals or semiconductors an evaporation assisted by the rectification of the optical field at the surface. In this paper the principle of the 3DAP is presented and the underlying physics involved in the field evaporation assisted by femtosecond laser pulses is discussed.