Practical Electron Microscopy and Database

The energy shift of the zero-loss peak can be accurately measured by determining the centroid of a Gaussian distribution, which is fitted to the zero-loss peak of each low-loss EELS spectrum. The fitting is performed using a linear least-squares method, ensuring that the Gaussian model closely matched the experimental data. A fitting range from -10 eV to +10 eV around the zero-loss peak was employed, capturing the peak's full width and minimizing the influence of noise and other artifacts. This process is repeated for each position across the sample, resulting in the creation of a 3D energy-shift map, denoted as ΔE(x,y,θ), where x and y represent the spatial coordinates of the probe across the sample, and θ represents the energy shift at each point. This comprehensive map provides detailed insights into the spatial variations of energy shifts across the sample, reflecting the impact of local electronic, structural, and environmental factors on the measured EELS data.