Looking underneath fullerenes on Au(110): Formation of dimples in the substrate

The adsorption of organic molecules on metal surfaces can lead to complex nanostructuration of the supporting substrate. The precise atomistic and electronic structures of the C60/Au(110) interface are unveiled by combining synchrotron-based diffraction and spectroscopic techniques with density functional theory calculations. We show that the interaction between C60 molecules with Au(110) surface induces a massive interface reorganization, which leads to the $\mathrm{Au}\left(110\right)\text{−}p(6\times 5)$ substrate reconstruction and to the formation of surface nanodimples. The fullerenes are hosted by these nanodimples, which are one and two layers deep. We provide evidence that the larger contact area between the C60 and the metal, which results from the substrate rearrangement, allows for the formation of strong directional C-Au bonds.

Figure 1

(Color online) (a) Initial model for LS refinement based on Ref. 3. Darker atom tonalities refer to deeper atoms from the surface. (b) Optimized interface structure: Best fit is obtained when suppressing some gold atoms (marked with X) from the initial model. (c) Top and lateral views of the ${\mathrm{C}}_{60}∕\mathrm{Au}\left(110\right)\text{−}p(6\times 5)$ interface structure. The transparent spheres simulating the C60 molecules indicate absence of preferential orientation.

Figure 2

(Color online) (a) Experimental and calculated in-plane data of the ${\mathrm{C}}_{60}∕\mathrm{Au}\left(110\right)\text{−}p(6\times 5)$ surface reconstruction. Measured values and their associated uncertainties are proportional to the radii of the two empty semicircles. Filled semicircles are proportional to calculated values obtained from the final structure model shown in Fig. 1c. [(b) and (c)] Experimental (dots) and calculated (continuous lines) data for several fractional order (b) and crystal truncation rods (c) from final structure (values close to the curves indicate their corresponding offset for better visualization).

Figure 3

(Color online) (a) Bonding charge density obtained from DFT calculation of the structure model shown in Fig. 1c. Positive and negative electron density isosurfaces $(\mid 0.005\mid \mathrm{e}∕{\mathrm{\AA }}^3)$ are displayed as red (dark gray) and light gray areas, respectively. (b) Experimental PE spectrum (red), calculated DOS (black) for C60/Au(110), and (c) C p-DOS for an isolated C60 molecule. (d) Conduction band IPE data and C p-DOS for C60/(110). PE, IPE, and C p-DOS spectra are displayed as red (up triangles), blue (filled circles), or black (without symbol) lines, respectively.