Spectrum of the interaction potential between He and as-deposited self-assembled monolayers of decanethiol chemisorbed on Au(1 1 1)

In this article, full monolayers of standing-up molecules of decanethiol chemisorbed on Au(1 1 1) have been grown at 275 K in ultrahigh vacuum and studied by low energy He atom scattering in the temperature range between 40 and 60 K. The specular peak intensity has been measured on the as-deposited layer and features associated to resonances with bound states of the He atom interacting with the CH3 groups of the organic molecules have been observed. Through the analysis of the angular position of these features four bound state levels have been determined. The comparison between the levels determined for the as-deposited monolayer and those determined for the annealed one shows that the spectra are sensitive to the annealing process.