Site selective inelastic electron tunneling spectroscopy probed by isotope labeling

Area of Science:

• Surface science
• Molecular electronics
• Spectroscopy

Background:

• Alkanethiol self-assembled monolayers are crucial in molecular electronics.
• Inelastic electron tunneling spectroscopy (IETS) probes molecular vibrations.
• Understanding vibrational modes is key to controlling electron transport.

Purpose of the Study:

• To identify specific molecular vibrations active in IETS of alkanethiols.
• To determine the contribution of different molecular parts to the inelastic signal.
• To validate experimental findings with theoretical calculations.

Main Methods:

• Utilized isotope labeling, specifically selective deuteration of alkanethiol molecules.
• Performed inelastic electron tunneling spectroscopy (IETS).
• Conducted first principles calculations for theoretical validation.

Main Results:

• Unambiguously identified molecular vibrations active in IETS.
• Demonstrated approximately equal contribution of different molecular segments to the inelastic signal.
• First principles calculations confirmed experimental observations.

Conclusions:

• Established a method for assigning vibrational modes in IETS using isotope labeling.
• Provided insights into electron transport mechanisms through alkanethiol molecules.
• Highlighted the utility of combined experimental and computational approaches.