Selectivity in vibrationally mediated single-molecule chemistry.

Area of Science:

• Surface Science
• Chemical Physics
• Nanotechnology

Background:

• Selective excitation of molecular vibrations influences chemical reaction dynamics.
• Lasers have traditionally been used for mode-selective chemistry.
• Inelastic electron tunneling can also excite vibrations in adsorbed molecules.

Purpose of the Study:

• To demonstrate selective control over individual ammonia molecule reactions using inelastic electron tunneling.
• To investigate the possibility of directing reactions towards translation or desorption.
• To explore the use of scanning tunneling microscopy for low-yield, low-power single-molecule event studies.

Main Methods:

• Utilized inelastic electron tunneling microscopy (ITEM) on ammonia molecules adsorbed on a Cu(100) surface.
• Tuned electronic tunneling current and energy to selectively excite specific molecular vibrations.
• Observed and differentiated between molecular translation and desorption events.

Main Results:

• Demonstrated selective induction of either translation or desorption of individual ammonia molecules.
• Showed that tuning electron tunneling parameters activates either the stretching vibration or the inversion of ammonia.
• Successfully probed single-molecule events with very low yield and power.

Conclusions:

• Inelastic electron tunneling provides a tunable method for mode-selective chemistry at the single-molecule level.
• Scanning tunneling microscopy is a powerful tool for investigating low-yield single-molecule reaction pathways.
• This approach opens avenues for studying complex reactions not accessible by conventional methods.