Transition from van-der-Waals to H Bonds dominated Interaction in n-Propanol physisorbed on Graphite

TL;DR

This study investigates how the interaction mechanism in n-propanol on graphite transitions from van-der-Waals forces to hydrogen bonding, revealing multilayer behavior, a bilayer in the fourth layer, and a possible wetting transition.

Contribution

It provides experimental evidence of the transition from van-der-Waals to hydrogen-bond dominated interactions in n-propanol multilayer adsorption on graphite.

Findings

First three layers follow FHH-model consistent with van-der-Waals interactions.

Fourth layer forms a bilayer, indicating a change in interaction regime.

Evidence of a wetting transition related to hydrogen bonding.

Abstract

Multilayer sorption isotherms of 1-propanol on graphite have been measured by means of high-resolution ellipsometry within the liquid regime of the adsorbed film for temperatures ranging from 180 to 260 K. In the first three monolayers the molecules are oriented parallel to the substrate and the growth is roughly consistent with the Frenkel-Halsey-Hill-model (FHH) that is obeyed in van-der-Waals systems on strong substrates. The condensation of the fourth and higher layers is delayed with respect to the FHH-model. The fourth layer is actually a bilayer. Furthermore there is indication of a wetting transition. The results are interpreted in terms of hydrogen-bridge bonding within and between the layers.