Submolecular-scale control of phototautomerization

Area of Science:

• Surface science
• Photochemistry
• Nanotechnology

Background:

• Optically activated reactions are fundamental to biological processes and chemical applications.
• Current methods for controlling on-surface photochemistry lack atomic-scale precision.

Purpose of the Study:

• To demonstrate atomic-scale control over photochemistry using confined electromagnetic fields.
• To investigate the phototautomerization of free-base phthalocyanine with submolecular precision.

Main Methods:

• Utilizing the electromagnetic field confinement at a scanning tunneling microscope (STM) tip apex.
• Employing laser excitation wavelength and STM tip position to control reaction dynamics.
• Applying atomically resolved tip-enhanced photoluminescence spectroscopy and hyperspectral mapping.

Main Results:

• Achieved submolecular precision in driving phototautomerization reactions.
• Demonstrated control over reaction rates and tautomer populations.
• Unraveled an excited-state mediated photochemical process.

Conclusions:

• The STM tip-enhanced optical approach enables unprecedented control over on-surface photochemical reactions.
• This methodology provides insights into photochemical reaction mechanisms.
• The strategy is potentially applicable to controlling complex on-surface reactions with atomic precision.