@article{Yamanishi2016, author = {Junsuke Yamanishi and Takashi Tokuyama and Yoshitaka Naitoh and Yan Jun Li and Yasuhiro Sugawara}, title = {Distance dependence of atomic-resolution near-field imaging on α-Al2O3 (0001) surface with respect to surface photovoltage of silicon probe tip}, year = {2016}, journal = {Nano Research}, volume = {9}, number = {2}, pages = {530-536}, keywords = {near-field scanning optical microscopy, near field, surface photovoltage, α-Al2O3 (0001), force detection}, url = {https://www.sciopen.com/article/10.1007/s12274-015-0934-4}, doi = {10.1007/s12274-015-0934-4}, abstract = {Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by the optical near field on the surface is measured as the electrostatic force. We demonstrated atomicresolution imaging of the near field on the α-Al2O3 (0001) surface of a prism. We investigated the spatial distribution of the near field by scanning at different tip-sample distances and found that the atomic corrugation of the near-field signal was observed at greater distances than that of the atomic force microscopy signal. As the tip-sample distance increased, the normalized signal-to-noise ratio of the near field is in a gradual decline almost twice that of the frequency shift (Δf).} }