STM images of five different configurations after adsorption of meta-chloronitrobenzene on Cu(111) identified as [(a) and (b)] ortho-chloronitrobenzene (-ClNB), [(c) and (d)] meta-chloronitrobenzene (-ClNB), and (e) para-chloronitrobenzene (-ClNB). and denote that chlorine is adsorbed to the right hand side and left hand side of the nitro group, respectively, reflecting adsorption induced chirality. (f) Line scans above isomers taken along dashed lines marked in (a), (c), and (e). The experiments were performed at at a bias voltage of and a tunneling current of .
Assumed adsorption geometry for chloronitrobenzene molecules on Cu(111). (a) para-ClNB with chlorine sitting on bridge site, (b) meta-ClNB, and (c) ortho-ClNB. On the right-hand side, a side view showing that the reconstruction tilts the hydrogens and the substitutes slightly away from the surface.
Simulated STM images: (a) para-ClNB, (b) meta-ClNB, and (c) ortho-ClNB. The comparison between simulated and measured STM images is presented in (d), where the model of the -ClNB is taken from the theoretical simulations. The red/gray contours ellipses and circles are obtained by drawing the lines over the nitro group and the chlorine in calculated STM images, while the black contours are the outer shapes of the molecules as they appear in measured STM images.
The DOS of the orbital of the Cu atom diminishes in the adsorption. Dot-dashed line is the DOS of a surface Cu atom far from the adsorbate; and on solid line the DOS of the Cu atom under the phenyl ring.
Combined DOS of and orbitals of [(a) and (b)] oxygen atoms and (c) chlorine atom of ClNB adsorbed on Cu(111) in three different configurations. The symmetry between the two oxygens is broken when the chlorine is brought to the orthoconfiguration, and a strong mixing of states can be observed between the chlorine and the other oxygen.
Frontier molecular orbitals for (a) para-ClNB, (b) meta-ClNB, (c) ortho-ClNB computed with the DMOL3 code, and (d), meta-ClNB computed with the TB method. In para- and metaconfigurations, the HOMO is localized in the nitro group and the HOMO-1 and HOMO-2 consist solely of chlorine orbitals, whereas in the orthoconfiguration they are blended together.
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