Reliable preparation and regeneration of well-defined single-atom tips through laser annealing.

Single-atom tips (SATs) have crucial scientific and technological applications, such as in scanning probe microscopy and charged particle beam technology. We reported a reliable method of preparing and regenerating noble metal-covered W(111) SATs through laser annealing at approximately 1000 K under ultrahigh vacuum. The field emission patterns obtained during laser heating revealed the self-assembly process of a pyramidal tip. The SATs can be regenerated through laser annealing tens of times with little change in sharpness, indicating a long lifetime. Various pyramidal SATs can be generated and regenerated using visible-light, near-infrared, mode-locked, and continuous-wave lasers at different polarizations relative to the tip axis. The generation of well-defined pyramidal SATs through laser annealing can facilitate various applications of SATs.