Directed assembly of fullerene on modified Au(111) electrodes

The nanometre limits of ballistic and diffusive hot-hole mediated nonlocal molecular manipulation

We report an experimental investigation into the surface-specific and experimental limits of the range of STM induced nonlocal molecular manipulation. We measure the spot-size of the nonlocal manipulation of bromobenzene molecules on the Si(111)-7 × 7 surface at room temperature at two voltages and for a wide range of charge-injection times (number of hot charge-carriers) from 1 s up to 500 s. The results conform to an initially ballistic, 6-10 nm, and then hot-hole diffusive, 10-30 nm, transport away from the localised injection site. This work gives further confirmation that nonlocal molecular manipulation by STM directly reveals the ultrafast transport properties of hot-charge carriers at surfaces.

Imaging and Dynamics of Water Hexamer Confined in Nanopores

Epitaxial two-dimensional (2D) nanostructures with regular patterns show great promise as templates for adsorbate confinement. Prospectively, employing 2D semiconductors with reduced density of states leads to a long excited-state lifetime that allows us to directly image the dynamics of the adsorbate. We show that epitaxial blue phosphorene (blueP) on Au(111) provides such a platform to trap water molecules in the periodic nanopores without formation of strong bonds. The trapped water aggregate is tentatively assigned to a hexamer based on our scanning tunneling microscopy studies and first-principles calculations. Real-space observation of conformational switching of the hexamer induced by inelastic electrons is achieved by using low-temperature scanning tunneling microscopy with molecular resolution. We found a localized interfacial charge rearrangement between the water hexamer and P atoms underneath that is responsible for the reversible desorption and adsorption of water molecules by changing the sample bias polarity from positive to negative, offering a promising strategy for engineering the electronic properties of blueP.