An approach to an objective background subtraction for elemental mapping with core-edges down to 50 eV: description,...

Area of Science:

• Materials Science
• Microscopy
• Biophysics

Background:

• Energy filtering transmission electron microscopy (EFTEM) requires accurate background subtraction for elemental mapping.
• The conventional three-window power-law method introduces systematic errors, particularly for low-energy core-edges.
• Accurate elemental distribution imaging is crucial for analyzing biological specimens.

Purpose of the Study:

• To develop a more accurate method for background subtraction in EFTEM elemental mapping.
• To overcome limitations of existing methods for low-energy core-edges.
• To enable objective elemental mapping for biological samples.

Main Methods:

• A generalized difference method using a third-order polynomial fit for background subtraction.
• Utilizing one or two pre-edge windows to model the background.
• Application to element detection in biological specimens, including iron and phosphorus.

Main Results:

• The new method provides accurate background subtraction, even for low-energy core-edges (50-100 eV).
• Demonstrated successful elemental mapping for the M2,3-edge of iron at 60 eV.
• Achieved a fivefold higher signal-to-noise ratio for phosphorus detection compared to the three-window method.

Conclusions:

• The generalized difference method offers objective and improved elemental mapping in EFTEM.
• This technique is particularly effective for analyzing low-energy core-edges in biological specimens.
• The method shows potential for detecting elements like calcium with minimal pre-edge imaging.