Adsorption and wetting structures of Kr on Pt(111) at 8 K and 45 K studiedby scanning tunneling microscopy

Adsorption and wetting structures of Kr on Pt(111) were studied using scann ing tunneling microscopy. The characteristics were different from those of Xe/Pt(111) and Xe/Cu(111). At 8 K, Kr atoms adsorbed on terraces and prefer ential adsorption to step edges was not observed. Kr atoms were imaged with 0.12 nm height and 1.0 nm full width at half maximum. With the additional exposure, adsorption at step edges occurred, with a slight preference for t he upper step edges. However, no evidence for the characteristic properties , such as repulsive interaction between adsorbates or modification of the e lectronic structures at step edges, was observed. With the rise in temperat ure to 45 K, Kr atoms on the terraces increased in size with hexagonal shap e, and wetting of the step edges began. In the wetting process, the lower s tep edge was more preferential, and the wetting region on both step edges g rew with a stripe shape-, the edge of the wetting region was not irregular but straight and parallel to the steps. In addition, the height of the Kr i mages decreased and showed two different values, namely, Kr stripes grown f rom the lower step edges were observed to have 0.10 nm height, 0.02 nm high er than those with a height of 0.08 nm grown on terraces or at upper step e dges. The obtained results indicate the existence of two different structur es, which may be attributed to the two structures previously observed by th e macroscopic analyses.