Vibrationally resolved fluorescence excited with submolecular precision.

Area of Science:

• Surface Science
• Molecular Spectroscopy
• Nanotechnology

Background:

• Single-molecule spectroscopy is crucial for understanding molecular behavior.
• Scanning tunneling microscopy (STM) offers atomic resolution for surface studies.
• Integrating optical techniques with STM can provide unprecedented insights into molecular properties.

Purpose of the Study:

• To demonstrate photon emission from individual porphyrin molecules using STM.
• To investigate molecular conformations and electronic states via vibrational spectroscopy.
• To establish STM as a tool for single-molecule fluorescence spectroscopy.

Main Methods:

• Utilizing tunneling electrons from an STM to excite photon emission.
• Adsorbing individual porphyrin molecules on an ultrathin alumina film on NiAl(110).
• Analyzing light-emission spectra and correlating with scanning tunneling spectroscopy data.

Main Results:

• Observed vibrational features in light-emission spectra sensitive to molecular conformations.
• Demonstrated spatial variations in light-emission spectra across different molecular regions.
• Successfully correlated electronic states with observed spectral features.

Conclusions:

• STM can induce and detect photon emission from single molecules.
• This technique allows for probing molecular conformations and electronic states at the single-molecule level.
• The integration of STM with optical spectroscopy opens new avenues for nanoscale chemical and physical investigations.