Raising flags: Applications of chemical marker groups to study self-assembly, chirality, and orientation of interfacial films by scanning tunneling microscopy

When used in conjunction with "chemical marker groups" (functionalities such as -Br and -COOH), scanning tunneling microscopy is a powerful tool for studying the properties of liquid-solid interfaces. Chemical markers serve as "flags" for the identification of interfacial structures, allowing, for example, the absolute chirality of optically active molecules self-assembling on a graphite surface to be determined. Subtle changes in the orientation of these chemical functionalities that affect the long-range order of interfacial films have also been observed and explored. Finally, alterations in self-assembly resulting from variations in adsorbate or substrate structure can be deduced by taking advantage of these STM "flags".