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Obtaining 3D Chemical Maps by Energy Filtered Transmission Electron Microscopy Tomography
Published on: June 9, 2018
A simple energy filter for low energy electron microscopy/photoelectron emission microscopy instruments
R M Tromp1, Y Fujikawa, J B Hannon
1IBM Research Division, T J Watson Research Center, PO Box 218, 1101 Kitchawan Road, Yorktown Heights, NY 10598, USA.
Summary
A simple energy filter was added to low energy electron microscopy (LEEM) and photoelectron emission microscopy (PEEM) instruments, enhancing their analytical capabilities without complex modifications. This setup achieves high energy resolution for detailed surface imaging and spectroscopy.
Area of Science:
- Surface Science
- Electron Microscopy
- Spectroscopy
Background:
- Low energy electron microscopy (LEEM) and photoelectron emission microscopy (PEEM) offer powerful surface analysis but can be limited in analytical depth.
- Existing electron energy filters for LEEM/PEEM are often complex, involving significant optical and mechanical modifications.
Purpose of the Study:
- To describe a simple, retrofittable energy filter for enhancing the analytical capabilities of existing IBM LEEM/PEEM instruments.
- To demonstrate the filter's performance in high-resolution imaging and spectroscopy of surfaces.
Main Methods:
- Integration of a single scanning aperture slit into the objective transfer optics of an existing LEEM/PEEM instrument.
- Utilizing a laboratory-based He I (21.2 eV) light source for surface spectroscopy.
- Employing a 4 eV energy loss Ag plasmon for imaging Ag nanowires on Si(001).
Main Results:
- Achieved very high energy resolution (ΔE/E = 2 × 10⁻⁵) and low non-isochromaticity (∼0.5 eV/10 µm).
- Enabled recording of selected area electron energy spectra and angular distributions with 0.15 eV resolution.
- Produced energy-filtered images with a 1.5 eV pass band and an estimated spatial resolution of ∼10 nm.
Conclusions:
- The simple energy filter significantly enhances the analytical capabilities of LEEM/PEEM instruments.
- The filter allows for detailed surface characterization, including spectroscopy and high-resolution imaging, with minimal instrument modification.
- Demonstrated applicability in analyzing surface phenomena and nanostructures.
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