Abstract:

Scanning tunneling microscopy (STM) and density functional theory (DFT) were used to investigate the adsorption sites of separable tert-butylamine (t-BA) molecules on a Cu(111) surface at 78 K. We developed a method that uses CO molecules on a co-adsorbed √3 ×√3 superstructure as markers for copper atoms on the surface lattice. This method revealed an on-top adsorption for t-BA on the Cu(111) surface. At low coverage, t-BA molecules preferentially adsorbed at the top sites of the Cu(111) surface and this was confirmed using a single CO molecule as a marker for a copper atom. DFT calculations were performed to study the most stable adsorption configuration of t-BA on the terrace of the Cu(111) surface at 78 K. Calculation results indicate that the top site is the most energetically preferred adsorption site for a single t-BA molecule on the terrace, which agrees well with the experimental results.

Key words: Scanning tunneling microscopy, Adsorption site, Single molecule, Co-adsorption, Density functional theory