Imaging Atomic-Scale Chemistry from Fused Multi-Modal Electron Microscopy

The chemical composition of specimens is revealed by spectroscopic techniques produced by inelastic interactions in the form of energy dispersive X-rays (EDX) or electron energy loss of the transmitted electrons (EELS). Unfortunately, the dose requirements for high-resolution chemical-spectroscopy often far exceed the dose limits of a specimen—chemical maps are noisy or missing entirely. More reliable interpretation of material structure is to be made in combination with elastically scattered electrons that can measure structure, but not chemistry, at high signal-to-noise ratios (SNR). The deluge of inelastic and elastic signals (i.e. modalities) are typically analyzed separately.

Here we introduce multi-modal electron microscopy, a technique that offers high SNR recovery (500% increase in favorable cases) of nanoscale material chemistry by leveraging correlated information encoded within both high-angle annular dark field (HAADF) and EDX / EELS. In all cases, Poisson noise in the raw chemical maps is virtually eliminated while maintaining structure at atomic resolution and notably lower electron doses than traditional approaches. Moreover, our multi-modal approach also recovers the specimen’s chemical relative concentration, allowing researchers to measure local stoichiometry.