Breakthrough in atomic resolution of deposited nano-objects
EuroFANAS project NOMCIS has achieved a breakthrough in overcoming one of the main limitations in atomic resolution studies of deposited nano-objects on insulating surfaces – the identification of ions in the imaged surface. This is an important step in characterization and technology realization, since since such surfaces are critical as model substrates in molecular electronics and nanocatalysis.
The approach relies on doping the insulating sample, in this case NaCl, with differently valent ions to form a distinct Suzuki structure on the surface. The Suzuki structure consists of replacing alternate cations with the dopant and a compensating cation vacancy. A detailed comparison between experiment and theory shows that all ions in the Suzuki structure can be unambiguously identified by force microscopy imaging. This identification is possible due to the geometry of the atomic Suzuki structure, which contrasts the situation on the pure NaCl or most other insulating surfaces, where unambiguous identification is not possible. It was demonstrated that the identification can be done independently of the tip-surface distance, of the chemical nature of the divalent impurity ions inside the Suzuki structure, and despite differences in surface termination.
The atomically resolved images makes Suzuki surfaces an attractive choice for investigations of deposited molecules and nanoparticles, particularly for nanomanipulation. The unambiguous identification makes it much easier to characterize deposited nano-objects and reaction products at the atomic scale. An additional benefit is the ability to nanotemplate the surface with Suzuki islands of different electronic and reactive character.
Reference:
Adam S. Foster, Clemens Barth, and Claude R. Henry, Chemical identification of ions in doped NaCl by scanning force microscopy, Phys. Rev. Lett. 102, 256103 (2009); selected for Virt. J. Nano. Sci. Tech. vol. 20, issue 2 (2009).
