Direct probing molecular twist and tilt in aromatic self-assembled monolayers

Using a nitrile tailgroup as a spectroscopic marker, both twist and tilt of the aromatic backbones in several typical aromatic SAMs on Au(111) have been directly determined in a single experiment. Whereas the exact value of the twist angle depends on the molecular architecture, it was found to be quite noticeable in all SAMs (40-50 degrees) and close to the respective value for aromatic bulk systems (32 degrees).