Figure 1

Self-assembled molecular ribbons. STM images of TBrPP-Co (a), and TBrPP-Cu (b), on Cu(111) showing ribbonlike self-assembled molecular assemblies. At higher resolution, a hexagonal close-packing of the molecules can be observed (c). The distance between the centers of two nearest neighbor molecules is 1.7 nm (imaging parameters: 1 V, 0.25 nA). (d) A differential conductance spectrum of a TBrPP-Co molecule inside the ribbon shows a dip (Kondo resonance), while that of TBrPP-Cu does not show any resonance around the surface Fermi level (0 V). The solid line represents the Fano line-shape fit to the data. The fit parameters are $q=0.38\pm 0.01$ and ${\epsilon }_K=7.11\pm 0.12\mathrm{mV}$. (e) The HOMO located at 0.7 eV (indicated with an arrow) is originated from the Co $d_z{}^2$ orbital (blue curve). This orbital is absent in the OMTS of TBrPP-Cu ribbon (red curve). The peaks located at the positive bias are the lowest unoccupied orbitals of TBrPP-Co and TBrPP-Cu molecules.Reuse & Permissions

Figure 2

Building molecular hexagon. The molecules from the ribbon (a) are removed by using an STM tip to create a hexagonal unit cell (circled) (b) [Imaging parameters: $28\mathrm{nm}\times 50\mathrm{nm}$, 1 V, 0.2 nA]. (See the STM movie for the hexagon creation [16]).Reuse & Permissions

Figure 3

Kondo temperature tuning. (a) A sequence of STM images of different nn molecules created by removing one molecule at a time with the STM tip (left) from the hexagon and corresponding models (middle). The calculated electron standing wave patterns reveal a gradual exposing of the center molecule (indicated with a red circle) to the surface state electrons. Here white and black colors in the calculated images represent higher and lower electron densities, respectively. The black region under the molecular clusters indicates a reduction of surface electronic charge density. (b) The $dI/dV$ spectra are measured at each step by positioning the tip above the center molecule (indicated with red dot). The spectra are vertically and horizontally displaced for clarity. Horizontal displacements of 3 to 10 meV are taken for the spectra representing nn6, nn5, nn4, nn2, and nn1. (c) The plot of Kondo temperature as a function of the number of nearest neighbors.Reuse & Permissions

Figure 4

Different TBrPP-Co self-assemblies. (a) TBrPP-Co assemble in a parallel arrangement with lattice spacing $a=1.7$, $b=1.5\mathrm{nm}$. The Kondo temperature of $108\pm 12\mathrm{K}$ is determined from the $dI/dV$ tunneling spectroscopy (right, $q=-0.16\pm 0.01$ and ${\epsilon }_K=-0.4\pm 0.2\mathrm{meV}$). (b) In this TBrPP-Co cluster, the molecules assemble in a partial order of triangular arrangement. The triangular lattice has $a=1.7\mathrm{nm}$. The Kondo temperature of $111\pm 21\mathrm{K}$ is measured ($q=0.06\pm 0.01$ and ${\epsilon }_K=5.8\pm 0.4\mathrm{meV}$) from the $dI/dV$ data (right). [STM imaging parameters: 1 V, 0.4 nA. STM image size: $15\mathrm{nm}\times 9\mathrm{nm}$ (a) and $17\mathrm{nm}\times 10\mathrm{nm}$ (b)].Reuse & Permissions