Steering Electron-Induced Surface Reaction via a Molecular Assembly Approach

Area of Science:

• Surface science
• Physical chemistry
• Materials science

Background:

• Electrons act as reactants and catalysts in chemical processes.
• Electron-induced surface chemistry is significant but not fully understood, especially regarding molecular assembly.
• Controlling surface reactions at the molecular level is a key challenge.

Purpose of the Study:

• To investigate the impact of molecular assembly on electron-induced surface chemistry.
• To understand how molecular arrangement affects the reactivity of specific chemical bonds.
• To explore methods for precisely controlling electron-induced surface reactions.

Main Methods:

• Combined experimental scanning tunneling microscopy (STM) and theoretical density functional theory (DFT) studies.
• Investigated electron-induced C-Cl bond dissociation in 4,4″-dichloro-1,1′:3′,1′′-terphenyl (DCTP) on Cu(111).
• Analyzed DCTP in self-assembled structures and co-assemblies with bromine (Br) adatoms.

Main Results:

• Electron injection into the unoccupied molecular orbital of DCTP selectively dissociates the C-Cl bond.
• The energy threshold for C-Cl bond cleavage increases with the proximity of Br adatoms to DCTP molecules.
• This modulation of reactivity is attributed to energy shifts in the DCTP's unoccupied molecular orbital based on its assembly structure.

Conclusions:

• Molecular assembly plays a critical role in tuning electron-induced surface reactivity.
• Subtle changes in molecular arrangement can significantly alter chemical bond cleavage thresholds.
• This work demonstrates a pathway to precisely control surface chemistry via molecular assembly and electron injection.