Lead arachidate Langmuir-Blodgett (LB) films with two monomolecular layers were deposited on trimethyl-silylated glass substrates and studied by X-ray Photoelectron Spectroscopy. XP spectra of the O1s, C1s, Pb4f and Si2p lines were recorded. The completeness of the salt formation was assessed by the normalised intensity ratio of the carboxylic (-COO-) type carbon component with C1s B.E. at about 288.5 eV and that of the Pb cation.
The Layers-on-Plane model was applied with the following arrangement: the Pb-arachidate monolayer was considered as two sublayers due to the dissimilar nature of the two parts of the molecule. For the two sublayers, the physical constants of the octadecane and the lead acetate were used. The contribution of the silyl groups was neglected.
The calculated thickness of the lead arachidate monolayer was 28.8 Å, while the reported value in the literature is 28 Å. The realistic thickness ratio of the two sublayers justifies the presence of the Y-type structure.
M. Mohai, É. Kiss, A. Tóth, J. Szalma, I. Bertóti:
Preparation and Characterisation of Langmuir-Blodgett Type Arachidate Films.
Surf. Interface Anal. 34, 772 (2002).