Selected area nanodiffraction fluctuation electron microscopy for studying structural order in amorphous solids

We present a selected area nanodiffraction fluctuation electron microscopy (FEM) technique implemented on a conventional transmission electron microscope. Nanodiffraction patterns from a Pd-based metallic glass, collected using a selected area aperture 15 × 15 nm in effective size, display inhomogeneous speckling due to the small volume sampled. We compare the azimuthal intensity variance from these patterns to the spatial intensity variance from tilted dark-field measurements on the same specimens and find reasonable qualitative agreement, including features characteristic of medium-range order.