Momentum transfer resolved electron correlation microscopy

Electron correlation microscopy (ECM) characterizes local structural relaxation dynamics in fluctuating systems like supercooled liquids with nanometer spatial resolution. We have developed a new type of ECM technique that provides moderate resolution in momentum transfer or k space using five-dimensional scanning transmission electron microscopy. k-resolved ECM on a Pt_57.5Cu_14.7Ni_5.3P_22.5 metallic supercooled liquids measures rich spatial and momentum structure in the relaxation time data $\tau \left(r,k\right)$. Relaxation time maps $\tau \left(r\right)$ at each azimuthal k are independent samples of the material's underlying relaxation time distribution, and $\tau$ of radial k shows more complex behavior than the de Gennes narrowing observed in analogous X-ray experiments. We have determined the requirements for electron counts per k-pixel, number of k-pixels per speckle, and time sampling to obtain reliable k-resolved ECM data.