STM Imaging of Electron Migration in Real Space and Time: A Simulation Study

Area of Science:

• Surface science
• Molecular dynamics
• Ultrafast spectroscopy

Background:

• Understanding electron migration in molecules is crucial for molecular electronics and catalysis.
• Current methods for observing electron dynamics often lack sufficient spatial or temporal resolution.

Purpose of the Study:

• To demonstrate the capability of pump-probe ultrafast scanning tunneling microscopy (STM) for imaging molecular electron migration.
• To establish a simulation protocol for ultrafast STM experiments.

Main Methods:

• A simulation protocol mimicking ultrafast STM experiments was developed.
• Two laser pulses (pump and probe) were applied to a model molecular system.
• Time-integrated tip current was calculated against delay time and tip position to generate STM images.

Main Results:

• The simulation successfully generated STM images that track charge migration.
• The proposed method achieves atomistic spatial and femtosecond temporal resolutions.
• Suitable pump and probe parameters are key to successful imaging.

Conclusions:

• Pump-probe ultrafast STM is a viable technique for visualizing electron migration in molecules.
• This method offers unprecedented resolution for studying ultrafast charge dynamics at the molecular level.