Electron microscopy

electron diffraction of pharmaceutical nanocrystals

Electron image of a pharmaceutical nano-crystal.

Our highly sensitive detectors can be retrofitted to existing Transmission Electron Microscopes (TEMs) and obtain high-resolution 3D diffraction data from nano-sized crystals of beam sensitive material. These crystals are too small to be studied using high intensity X-rays at synchrotrons. Our detector system demonstrates how high sensitivity can be disruptive for electron microscopy applications where ultra-low intensity is imperative.

Refined atomic structure using ShellX.

Pictures and data are courtesy of van Genderen et al. Acta A (2016).

Electron 3D nano-crystallography with a Cheetah detector

In the case of electron diffraction, recent results in collaboration with the Jan Pieter Abrahams’ Lab at Leiden university show that complete sampling of Bragg spacings can be achieved with ASI’s Cheetah 120 or ASI’s first electron camera detector in combination with continuous crystal rotation. This detector holds a 512×512 pixels Timepix chip (pixel size 55 μm) and is of unprecedented sensitivity with a high dynamic range (13.5 bit) and a very high signal-to-noise ratio. Rotational electron diffraction data at room temperature of pharmaceutical compounds and protein nano-crystals was collected at 200 keV (λ=0.025 Å) with a frame rate of 9.1 fps at extreme low dose conditions (±0.01 e-.Å-2.s-1). Furthermore, it was demonstrated that in the case of pharmaceuticals, 50° of continuous rotation data could be collected at room temperature from 200 nm thin, compound nano-crystals showing high resolution Bragg spots up to 0.8 Å. The atomic structure could be solved using direct methods.

Pictures and data are courtesy of van Genderen et al. Acta A (2016).