A mass spectrograph that identifies atom position and processes an analyzed sample into the shape of a needle with a tip radius curvature of around 50 nm. It applies a laser pulse onto the sample under high voltage to ionize the atoms from the sample’s surface while simultaneously measuring the mass and position of those ions. Because ionization is detected when it is projected from the needle onto the surface of the detector, the magnification ratio of the projection exceeds 1 million, so the atom position can be identified at a sub-nanometer position resolution. By conducting this continuously, this method three-dimensionally analyzes the position and type of atoms evaporating sequentially from the surface of the sample.
(Shematic of 3DAP principle)

(SEM image of Nd-Fe-B magnet (left), STEM image of grain boundary (center), 3D atom map of Nd-enriched grain boundary phase in a Dy-diffusion processed Nd-Fe-B sintered magnet ~35×35×110 nm³(● Nd ● Ga ● Cu(right))

Broadening the applications of the atom probe technique by ultraviolet femtosecond laser, K. Hono et al., Ultramicroscopy 111, 576 (2011).

 The development of the microfabrication method using the focused ion beam (FIB) technique makes site specific 3DAP specimen preparation possible, such as grain boundaries, interphase interfaces, specific region of devices, nanowires etc..