PTMS alignment on Aluminium Oxide

This manuscript presents the results of a NEXAFS investigation of the adsorption of n-propyltrimethoxysilane (PTMS) on aluminium oxide surfaces. Although the NEXAFS measurement unambiguously detects the adsorbed PTMS molecules, no preferential alignment of the PTMS molecules is observed. The absence of molecular alignment of the PTMS molecule is described in terms of a simple model for the packing of the adsorbed PTMS molecules. It is concluded that the PTMS surface coverage it too low for film alignment to occur. This low coverage, along with the short length alkyl chain, means that there is insufficient Van der Waals interaction between the neighbouring propyl chains and hence the surface film is predominantly disordered.