Functional Group Mapping by Electron Beam Vibrational Spectroscopy from Nanoscale Volumes

Area of Science:

• Materials Science
• Spectroscopy
• Nanotechnology

Background:

• Spatially resolved functional group analysis is crucial for understanding materials at the nanoscale.
• Existing surface techniques limit nanoscale mapping to material surfaces.
• Electron energy loss spectroscopy (EELS) offers a pathway for analyzing nanoscale volumes.

Purpose of the Study:

• To demonstrate the capability of vibrational EELS for nanoscale functional group mapping.
• To analyze the distinct linkers within a metal-organic framework (MOF) crystal-glass composite.
• To establish EELS as a tool for spatially resolved analysis of organic and metal-organic solids.

Main Methods:

• Vibrational Electron Energy Loss Spectroscopy (EELS) was employed.
• Scanning Transmission Electron Microscopy (STEM) was utilized.
• Correlated EELS at core ionization edges and X-ray energy dispersive spectroscopy (XEDS) were used for confirmation.

Main Results:

• Distinct carboxylate and imidazolate linkers in a MOF composite were successfully mapped.
• Domains smaller than 100 nm were observed.
• Spatial resolution better than 15 nm was achieved at composite interfaces.

Conclusions:

• Vibrational EELS provides nanoscale functional group analysis for crystalline and amorphous materials.
• This technique enables detailed characterization of MOF composites at the nanoscale.
• Spatially resolved functional group analysis using electron beam spectroscopy is established.