This paper is a community perspective on atom probe tomography, or APT, a method that maps the 3D chemical structure of materials at the nanoscale. The authors summarize recent experimental and modelling work on the basic physics of how atoms are removed and measured. They also describe major practical problems that affect how people collect, process, and interpret APT data. The paper is a written record of invited talks and discussions from a workshop held on August 4–5, 2024 in Alexandria, Virginia.

At a high level, the authors review new experiments and computer models that aim to explain common artifacts seen in APT. They focus on the process called field evaporation: atoms leave a needle-shaped sample when a strong electrostatic field lowers the energy needed for an atom to break free. Those atoms become ions, fly to a detector, and are identified by their time of flight. Because APT removes atoms one by one, the physical details of evaporation strongly affect the final 3D map.

The paper explains how APT is done and why it is delicate. Field evaporation is driven by short voltage or laser pulses that must be timed with sub-nanosecond precision. To avoid damaging the sample or overloading the detector, operators keep the average evaporation rate below one ion per pulse and often below 0.01 ions per pulse. A homogeneous evaporation rate across the analyzed surface is also important for making accurate maps.

The authors list several practical challenges with concrete examples. Assigning peaks in the mass spectrum (called ranging) can be hard, especially for oxides and nitrides where different ions produce overlapping peaks (for example, Mg++ can overlap with C+, and O+ can overlap with O2++). Detection efficiency is not perfect: modern detectors record roughly 52% of ions in systems with a reflectron (an ion-optics device that improves mass resolution but adds a shadowing mesh) and about 81% in straight-flight setups. Some materials show preferential ion loss, where specific elements are under-counted; examples include GaSb, Zn4Sb3 alloys, steels, and III‑nitride semiconductors. In III‑nitrides, nitrogen can be missed because it leaves as neutral fragments after molecules break apart in flight. Multi-hit events, when several atoms evaporate on the same pulse, also make detection and quantification harder, especially in strongly bonded materials.