2024/09/24 by Yueqing Shi, Liya Bi, Shi, Yueqing +13
Computer Science · Engineering · #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Molecular Junctions and Nanostructures #Quantum-Dot Cellular Automata #Surface Chemistry and Catalysis
paper · pdf · doi:10.48550/arxiv.2409.16485
openalex publication_date 2024/09/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Characterization of the structural and electron transport properties of single chiral molecules provides critical insights into the interplay between their electronic structure and electrochemical environments, providing broader implications given the significance of molecular chirality in chiroptical applications and pharmaceutical sciences. Here, we examined the topographic and electronic features of a recently developed chiral molecule, B,N-embedded double hetero[7]helicene, at the edge of Cu(100) supported NaCl thin film with scanning tunneling microscopy and spectroscopy. An electron transport energy gap of 3.2 eV is measured, which is significantly larger than the energy difference between the highest occupied and the lowest unoccupied molecular orbitals given by theoretical calculations or optical measurements. Through first principles calculations, we demonstrated that this energy discrepancy results from the Coulomb interaction between the tunneling electron and the molecule's electrons. This occurs in electron transport processes when the molecule is well decoupled from the electrodes by the insulating decoupling layers, leading to a temporary ionization of the molecule during electron tunneling. Beyond revealing properties concerning a specific molecule, our findings underscore the key role of Coulomb interactions in modulating electron transport in molecular junctions, providing insights into the interpretation of scanning tunneling spectroscopy features of molecules decoupled by insulating layers.