3 New publications in Advanced Functional Materials, Chemical Communications, and Journal of Physics: Condensed Matter

Date of news: 8 February 2017

In: Advanced Functional Materials

Externally Applied Manipulation of Molecular Assemblies at Solid-Liquid Interfaces Revealed by Scanning Tunneling Microscopy

A solid-liquid interface is a unique environment for the construction of
twodimensional molecular assemblies as a bottom-up approach towards
functional surfaces. Scanning tunneling microscopy (STM) has proven
itself as an excellent tool to characterize such surfaces at the
molecular level, by means of visualization. Many rules of design for
surface, solvent and chemical structure of the adsorbants have been
established, but methods to externally manipulate surface assemblies
after their formation are still under development. This feature article
deals with these manipulation methods at the solid-liquid interface and
evaluates, at the molecular level, the effects of temperature variation,
irradiation with light, applied electric or magnetic fields, mechanical
manipulation with the STM tip, and shear flow of the liquid phase.

In: Chemical Communications

Chemistry at the square nanometer: reactivity at liquid/solid interfaces revealed with an STM

For more than three decades the scanning tunnelling microscope (STM) has
proven to be an indispensable tool to image molecules adsorbed at a
surface at the highest detail possible. In addition to simply imaging
molecules, STM can also be applied to monitor dynamic surface phenomena,
including cemical reactions. By studying reactions at a surface at the
single molecule level, unique information about reaction mechanisms can
be obtained which remains hidden when conventional ensemble techniques
are used. Many STM studies of chemical reactions have been performed in
extreme environments like ultrahigh vacuum or high pressure chambers,
but these are far removed from conditions in which most chemical and
biological processes take place, i.e., in a liquid at ambient
atmospheres. This feature paper highlights the developments in the
relatively unexplored research area of investigating chemical reactions
with an STM at a liquid/solid interface under ambient conditions.
Covalent couplings between molecules, light-induced isomerisations,
reactions under electrochemical control, and complex multistep processes
and catalysis are discussed.

In: Journal of Physics: Condensed Matter

Porphyrin molecules boost the sensitivity of epitaxial graphene for NH3 detection

The sensitivity of quasi-free standing epitaxial graphene for NH3
detection is strongly enhanced by chemical functionalization with cobalt
porphyrins resulting in a detection limit well below 100 ppb.
Hybridization between NH3 and cobalt porphyrins induces a charge
transfer to graphene and results in a shift of the graphene Fermi-level
as detected by Hall measurements and theoretically explained by
electronic structure calculations.