Atomically resolved images of a (110)-(1 x 1) surface were obtained by means of non-contact atomic force microscopy under ultra-high vacuum. In contrast to previous scanning tunnelling microscopic studies, the outermost atoms of bridge-bound O ridges were seen as protruding rows. A high-resolution image of the surface revealed that the bridging O atoms ordered, with a (1 x 1) periodicity, on terraces. Point O-atom defects were also seen as dark spots.

K.Fukui, H.Onishi, Y.Iwasawa: Physical Review Letters, 1997, 79[21], 4202-5