Infrared vibrational nanocrystallography and nanoimaging

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Low-symmetry molecular solids and polymers exhibit anisotropic charge transport.
• Molecular orientation and disorder dictate macroscopic material properties.
• Conventional imaging techniques struggle to resolve nanoscale molecular arrangements.

Purpose of the Study:

• To develop a novel optical nanocrystallography method for nanoscale imaging.
• To determine crystalline phases and molecular orientation in organic materials.
• To map nanoscale heterogeneity and disorder in functional molecular solids.

Main Methods:

• Combined scattering-type scanning near-field optical microscopy (s-SNOM) with optical antenna and tip-selective infrared vibrational spectroscopy.
• Utilized symmetry-selective probing of molecular bond orientation.
• Achieved nanometer spatial resolution for imaging.

Main Results:

• Determined crystalline phases and orientation in perylenetetracarboxylic dianhydride (PTCDA) films and aggregates.
• Mapped disorder within and between individual nanoscale domains.
• Provided correlative hybrid imaging of nanoscale heterogeneity.

Conclusions:

• The developed technique offers unprecedented insight into defect formation and propagation during growth.
• This method advances the understanding of functional molecular solids.
• Enables precise control over material properties through nanoscale structural analysis.