Effect of sample thickness, energy filtering, and probe coherence on fluctuation electron microscopy experiments

Area of Science:

• Materials Science
• Electron Microscopy
• Nanotechnology

Background:

• Fluctuation electron microscopy (FEM) is a technique used to measure spatial fluctuations in nanodiffraction patterns.
• Understanding the factors influencing FEM measurements is essential for accurate material characterization.

Purpose of the Study:

• To experimentally investigate the impact of sample thickness, zero-loss energy filtering, and probe coherence on fluctuation electron microscopy (FEM) measurements.
• To determine the optimal conditions for obtaining reliable quantitative FEM data.

Main Methods:

• Experiments were conducted using nanodiffraction within a transmission electron microscope (TEM).
• The variance (V) of spatial fluctuations in nanodiffraction was measured under varying conditions.
• Key parameters investigated included sample thickness, the use of zero-loss energy filtering, and probe coherence.

Main Results:

• The variance (V) was found to be inversely proportional to sample thickness.
• Zero-loss energy filtering consistently increased the measured variance (V).
• Increased probe coherence led to a higher variance (V).

Conclusions:

• Sample thickness, energy filtering, and probe coherence significantly influence FEM measurements.
• Careful control of these experimental parameters is necessary for quantitative accuracy in FEM.
• The findings provide guidance for optimizing FEM experiments and data interpretation.