Deposition of Ca on the 2H-NbSe2 surface: Competing processes.

The interaction of Ca evaporated in vacuum onto a 2H-NbSe2 surface held at room temperature was studied by photoelectron spectroscopy. Indications of an intercalation reaction were observed initially, but larger Ca depositions resulted in a layer-breaking reaction producing a disordered overlayer of varying compositions. The layer-breaking reaction is likely due to the intercalation compound becoming unstable as the local Ca concentration exceeds the threshold value.

Stabilization of the misfit layer compound (PbS)1.13TaS2 by metal cross substitution.

Photoemission microspectroscopy on the layered misfit compound (PbS)1.13TaS2 provides direct evidence for Ta substitution into PbS layers as well as for Pb substitution into TaS2 layers. This metal cross substitution alters the charge balance between alternating layers and can explain the remarkable stability of (PbS)1.