Medium-range order in molecular materials: fluctuation electron microscopy for detecting fullerenes in disordered...

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Disordered carbons and graphitic materials are crucial in various applications.
• Detecting fullerenes, like buckminsterfullerene (C(60)), within these materials is challenging.
• Curvature in layered materials affects their structural and electronic properties.

Purpose of the Study:

• To identify unique signatures of C(60) in disordered carbons using fluctuation electron microscopy (FEM).
• To establish FEM as a sensitive technique for detecting highly curved, pentagon-rich fullerenes.
• To correlate spectral features with the structural characteristics of fullerenes and graphitic materials.

Main Methods:

• Utilizing fluctuation electron microscopy (FEM) to analyze disordered carbon samples containing C(60).
• Analyzing normalized variance peaks in diffraction patterns, specifically at 7.1 nm(-1).
• Performing FEM simulations to identify fullerene-specific peaks (F(1), F(2), F(3)) at various Q values.

Main Results:

• A distinct normalized variance peak at 7.1 nm(-1) was observed in C(60)-containing samples, indicative of tight curvature.
• This 7.1 nm(-1) peak is linked to the in-plane carbon-carbon bond distance in graphene, becoming observable due to structural interruptions.
• FEM simulations confirmed additional fullerene-signature peaks at 10.6 nm(-1) (F(2)) and 12.4 nm(-1) (F(3)).

Conclusions:

• FEM is a highly sensitive method for detecting dilute amounts of C(60) in disordered graphitic carbon.
• The identified spectral peaks serve as unique indicators of highly curved, pentagon-rich fullerenes.
• Structural interruptions, such as those caused by 5-rings in C(60), enable the observation of diffraction normally forbidden in planar graphene.