Calibrating thermal and scanning tunnelling microscope induced desorption and diffusion for the chemisorbed...

The precise calibration of thermally driven processes in scanning tunnelling microscope (STM) manipulation experiments, especially at room temperature and above, is necessary to uncover an accurate picture of non-thermal dynamical processes such as desorption induced by electronic transitions, driven by the STM current. Here we probe the displacement (the sum of desorption and diffusion) of chlorobenzene molecules chemisorbed on the Si(111)-7 × 7 surface, induced both by the STM electrical current and by heat. We also establish truly passive imaging inspection parameters. The activation energy for pure thermal displacement is 580 ± 20 meV, possibly associated with excitation to a physisorbed precursor state. STM induced displacement shows a marked decrease with increasing temperature, once the thermal effects are removed.