Multi-Channel Exploration of O Adatom on TiO₂(110) Surface by Scanning Probe Microscopy

We studied the O₂ dissociated state under the different O₂ exposed temperatures with atomic resolution by scanning probe microscopy (SPM) and imaged the O adatom by simultaneous atomic force microscopy (AFM)/scanning tunneling microscopy (STM). The effect of AFM operation mode on O adatom contrast was investigated, and the interaction of O adatom and the subsurface defect was observed by AFM/STM. Multi-channel exploration was performed to investigate the charge transfer between the adsorbed O and the TiO₂(110) by obtaining the frequency shift, tunneling current and local contact potential difference at an atomic scale. The tunneling current image showed the difference of the tunneling possibility on the single O adatom and paired O adatoms, and the local contact potential difference distribution of the O-TiO₂(110) surface institutively revealed the charge transfer from TiO₂(110) surface to O adatom. The experimental results are expected to be helpful in investigating surface/interface properties by SPM.