New mechanism for single atom manipulation

Scanning tunneling microscope (STM) investigations of the step roughening of Ag(110) have shown that the STM tip extracts atoms from otherwise stable steps even at typical imaging conditions. Detailed analyses of single STM scans reveal that none of the so far known lateral manipulation mechanisms (pushing, pulling, sliding) account for the observed atom extraction. The Ag atoms rather follow the energetically favorable path of a tip induced exchange process, similar to the concerted motion proposed previously for the diffusion on fcc(110) surfaces including a metastable and thus experimentally detectable dumbbell transition state.