SURFACE-STRUCTURES OF LAYERED COMPOUNDS TREATED WITH ALKALI-METAL HYDROXIDE SOLUTIONS STUDIED BY SCANNING-TUNNELING-MICROSCOPY

Ordered 2 X 2 and root 3 X root 3 superstructures with charge density modulation were observed by scanning tunneling microscopy (STM) on hig hly oriented pyrolytic graphite surfaces treated with MOH (M=Na, K) aq ueous solutions. Charge transfer from intercalants to host graphite wa s observed, as previously seen on stage-1 alkali-metal intercalations. On the other hand, for the MoS2 crystal treated with the same solutio ns, the host MoS2 lattice was observed together with island structures with low charge density formed by intercalants. Some electronic state s seemed to be formed between the MoS2 band gap.