Probing surface properties of organic molecular layers by scanning tunneling microscopy

Peptide-based self-assembled monolayers (SAMs): what peptides can do for SAMs and vice versa

“…It uses a sharp metal tip (one electrode of the tunnel junction) placed close (0.3-1 nm) to the surface to be investigated, by applying an electrical voltage to the tip or to the sample (10 mV-1 V), the surface can be sensed/imaged. 213 The STM is versatile enough to be used in a wide range of environments, from ultrahigh vacuum (UHV) to ambient air, water, and other liquids or gases, and temperatures down to millikelvin and as high as more than 1000 K. STM is distinguished from most other surface characterization methods by its unique capacity to probe the topographical and electrical features of plain surfaces with high spatial resolution, down to atomic scale. 213 For instance, Gatto and co-workers used STM to characterize the topography of SAMs formed by a hexapeptide (including five Aib residues and a Trp unit functionalised at the N-terminus with a lipoic group for binding to an Au substrate).…”

Molecular Self-Assembly and Adsorption Structure of 2,2′-Dipyrimidyl Disulfides on Au(111) Surfaces

“…Self-assembled monolayers (SAMs) provide a very convenient and powerful method to control the surface and interface characteristics of various metal surfaces via modifying the chemical structure of adsorbates with different active anchoring groups and molecular backbones [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Due to their advantages, SAMs have been applied to various nanotechnological applications in nanopatterning [ 1 ], biosensors [ 11 ], bioelectronics [ 12 ], solar cells [ 13 , 14 ], and molecular electronics [ 15 , 16 , 17 , 18 ].…”

“…It is important to understand the formation and surface features of 2PymS SAMs on Au(111) at a molecular scale, from both a fundamental and practical point of view [ 1 , 2 , 3 ]. Therefore, 2PymS SAMs on Au(111) derived from the 2,2′-dipyrimidyl disulfide (DPymDS) were examined using STM and X-ray photoelectron spectroscopy (XPS) as a function of solution concentration and pH.…”