“Liquid” and “Solid” Films
Morphological evolution of metal stearates show distinct growth modes that stem from the fact that amphiphiles of this type have either unidentate or bidentate coordination in their headgroup. More specifically, absence of in-plane dipolar forces in MnSt/CoSt headgroups, along with FM type “fully wetting” films obtained from them, point to a “liquid-like” character of these layers, in particular, where molecules are in symmetric configuration. In sharp contrast to this, the CdSt and ZnSt films exhibit VW type “island” growth along with presence of in-plane dipolar forces in their headgroup. In the previous chapters, we have shown how the coordination and hence the geometry of the metal-carboxylate headgroup decides the presence or absence of long-range intermolecular forces through the presence or absence of dipole moment, and have hinted that it may control the liquid-like or solid-like behavior of the corresponding multilayers. In this chapter, we will compare the height correlations in monolayers and multilayers of amphiphilic salts of two different divalent metals, Cd and Co, deposited on amorphous silicon substrate to bring out their essential differences as “solid” or “liquid”-like, respectively.