An STM study of the potassium-induced removal of the Ni(100)(2×2)p4g-N reconstruction

Coadsorption of potassium at step edges on the Ni(100)(2 × 2)p4g-N reconstructed surface

“…Figure 1 shows a 100 × 100 Å 2 area of the Ni(100)(2 × 2)p4g-N surface with a single step in the centre of the image running predominantly along the [0 11] direction and some more jagged steps in the upper and lower sections of the image (here and elsewhere we have labelled the specific directions shown as [010] and [001] for clarity). Under the tunnelling conditions used here (see the figure caption for details), the underlying metal atoms are not imaged, and the nitrogen atoms can clearly be seen on the terraces [10]. The surface has been dosed with a potassium coverage of 0.10 ± 0.05 ML.…”

“…In previous work, we have characterized this coadsorption system using low-energy electron diffraction (LEED) and angle-resolved photoemission spectroscopy (ARPES) [8], surface x-ray diffraction (SXRD) [9], and scanning tunnelling microscopy (STM) [10]. LEED studies revealed a change from a (2×2)p4g pattern to a c(2×2) pattern at a potassium coverage of ∼0.16 monolayers (ML) and the ARPES work focused on the differences in electronic structure between the p4g and c(2 × 2) systems [8].…”

“…We found that the reconstruction is removed and the nickel atoms revert to their bulk-like positions. In the previous STM work we focused on the mechanism for the removal of the reconstruction, finding that the reconstruction is lifted locally around isolated potassium atoms; and that initial adsorption of potassium takes place at step edges [10].…”