Photoelectron Spectroscopy of the Adsorption of Amino Acids on Surfaces: Glycine on Si(O₂)

We have studied chemically adsorbed glycine on the hydrophilic surface of the oxidized surface of silicon. A stable adsorbate layer is formed, which consists of zwitterionic glycine molecules. Most importantly, these zwitterionic molecules have a tendency for orientation in a direction perpendicular to the substrate surface, with COO- groups away from the surface and the NH3+ groups toward the surface.