Effect of Annealing on 4- and 3-Pyridinethiol Self-assembled Monolayers on Au(111) and Au(100) Studied by High-resolution Electron Energy Loss Spectroscopy

Abstract

The effect of annealing on 4-PySH and 3-PySH SAMs on Au(111) and Au(100) substrates was examined using high-resolution electron energy loss spectroscopy (HREELS) for the first time. At 300 K, the surfaces of 4- and 3-PySH SAMs on Au(111) were partially covered with artifacts. However, after annealing at the appropriate temperature, clear HREEL spectra of 4-PySH and 3-PySH SAM on Au(111) were recorded, and both the 4-PySH and 3-PySH molecules adsorbed in a flat orientation. In contrast, on Au(100), the HREEL spectra of 4-PySH and 3-PySH SAMs prepared at 300 K revealed that the pyridine rings are oriented almost perpendicular to the surface. Annealing at an appropriate temperature had a dramatic effect on the surface structure of the 4-PySH and 3-PySH SAMs: Both the 4- and 3-PySH molecules adsorbed in a flat orientation.