Light Element (C, N, O) Quantification by EDXS: Application to Meteorite Water Content and Organic Composition

Area of Science:

• Materials Science
• Planetary Science
• Biology

Background:

• Accurate quantification of light elements (C, N, O) in a transmission electron microscope (TEM) is crucial but challenging.
• Existing methods often lack precision for these elements, hindering research in various scientific fields.

Purpose of the Study:

• To develop a precise method for quantifying light elements using energy-dispersive X-ray spectroscopy (EDXS) in a TEM.
• To address challenges in X-ray absorption correction and K-factor determination for accurate elemental analysis.

Main Methods:

• Utilized sensitive windowless silicon drift detectors and custom Python routines for hyperspectral data processing.
• Determined K-factors using wedge-shaped focused ion beam sections and corrected for X-ray absorption via the revisited-two-lines method.
• Experimentally determined mass absorption coefficients to account for X-ray self-absorption effects, particularly for iron L lines.

Main Results:

• Achieved accurate quantification of nitrogen to carbon (N/C) ratios in organic matter with better than 5 at.% accuracy.
• Enabled precise oxygen quantification, sufficient for inferring hydroxyl content in phyllosilicates.
• Identified and corrected for X-ray self-absorption at the iron edge, improving accuracy for iron L lines.

Conclusions:

• The developed EDXS approach offers a robust solution for light element quantification in TEM.
• This method significantly advances the analysis of complex samples, including meteoritic materials.
• Improved accuracy in elemental quantification opens new avenues for research in materials science, biology, and planetary science.