  Energy dispersive X-ray (EDX) spectroscopy in the transmission electron
microscope is a key tool for nanomaterials analysis, providing a direct link
between spatial and chemical information. However, using it for precisely
determining chemical compositions presents challenges of noisy data from low
X-ray yields and mixed signals from phases that overlap along the electron beam
trajectory. Here, we introduce a novel method, non-negative matrix
factorisation based pan-sharpening (PSNMF), to address these limitations.
Leveraging the Poisson nature of EDX spectral noise and binning operations,
PSNMF retrieves high quality phase spectral and spatial signatures via
consecutive factorisations. After validating PSNMF with synthetic datasets of
different noise levels, we illustrate its effectiveness on two distinct
experimental cases: a nano-mineralogical lamella, and supported catalytic
nanoparticles. Not only does PSNMF obtain accurate phase signatures, datasets
reconstructed from the outputs have demonstrably lower noise and better
fidelity than from the benchmark denoising method of principle component
analysis.
