On the use of ionization cross sections in analytical electron microscopy

Area of Science:

• Materials Science
• Analytical Chemistry
• Physics

Background:

• Quantitative microanalysis in analytical electron microscopy relies on accurate ionization cross section (Q) values.
• Determining Q is crucial for calculating kappa AB factors, essential for elemental quantification.
• Existing methods for Q determination have limitations.

Purpose of the Study:

• To compare two distinct approaches for utilizing the ionization cross section (Q) in determining kappa AB factors.
• To evaluate the relative merits of experimental interpolation versus theoretical parameterization of Q.
• To inform the selection of the most effective method for quantitative microanalysis.

Main Methods:

• Approach 1: Interpolation of Q values from experimentally determined kappa AB factors at a fixed accelerating voltage.
• Approach 2: Theoretical parameterization of Q by fitting the Bethe expression to experimental Q values across a wide range of accelerating voltages (kV).
• Comparative analysis of the accuracy, applicability, and limitations of both methods.

Main Results:

• Experimental interpolation provides direct Q values but is limited to specific accelerating voltages.
• Theoretical parameterization offers a broader applicability across various kV but relies on model accuracy.
• The choice between methods depends on experimental conditions and desired precision.

Conclusions:

• Both experimental interpolation and theoretical parameterization of ionization cross section (Q) have distinct advantages and disadvantages.
• Theoretical parameterization using the Bethe expression offers greater flexibility for quantitative microanalysis over a range of accelerating voltages.
• Careful consideration of experimental parameters is necessary for selecting the optimal approach for accurate elemental quantification.