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 suc h as -Br and -COOH), scanning tunneling microscopy is a powerful tool for s tudying the properties of liquid-solid interfaces. Chemical markers serve a s "flags" for the identification of interfacial structures, allowing, for e xample, the absolute chirality of optically active molecules self-assemblin g on a graphite surface to be determined. Subtle changes in the orientation of these chemical functionalities that affect the long-range order of inte rfacial films have also been observed and explored. Finally, alterations in self-assembly resulting from variations in adsorbate or substrate structur e can be deduced by taking advantage of these STM "flags".