IMRE, A*STAR (Agency for Science, Technology and Research), 3 Research Link, 117602, Singapore.
ACS Nano. 2012 Apr 24;6(4):3230-5. doi: 10.1021/nn300110k. Epub 2012 Apr 5.
Electronic states of a molecule are usually analyzed via their decomposition in linear superposition of multielectronic Slater determinants built up from monoelectronics molecular orbitals. It is generally believed that a scanning tunneling microscope (STM) is able to map those molecular orbitals. Using a low-temperature ultrahigh vacuum (LT-UHV) STM, the dI/dV conductance maps of large single hexabenzocoronene (HBC) monomer, dimer, trimer, and tetramer molecules were recorded. We demonstrate that the attribution of a tunnel electronic resonance to a peculiar π molecular orbital of the molecule (or σ intermonomer chemical bond) in the STM junction is inappropriate. With an STM weak-measurement-like procedure, a dI/dV resonance results from the conductance contribution of many molecular states whose superposition makes it difficult to reconstruct an apparent molecular orbital electron probability density map.
分子的电子态通常通过它们在多电子 Slater 行列式的线性叠加中的分解来分析，这些行列式是由单电子分子轨道构建而成。通常认为扫描隧道显微镜 (STM) 能够绘制这些分子轨道。我们使用低温超高真空 (LT-UHV) STM 记录了大的单个六苯并蔻 (HBC) 单体、二聚体、三聚体和四聚体分子的 dI/dV 电导图谱。我们证明，将隧道电子共振归因于分子在 STM 结中的特殊π分子轨道（或σ 分子间化学键）是不恰当的。通过 STM 弱测量样过程，dI/dV 共振是由许多分子态的电导贡献产生的，这些分子态的叠加使得很难重建明显的分子轨道电子概率密度图。
