FEI Polara TEM (300kV)

CONFIGURATION

300kV, FEG, Helium / LN2 stage (9 Kelvin to 77 Kelvin), Gatan K2 Summit DED, and underneath that a custom-built Medipix detector (Abrahams group). The instrument is operated by Gatan's Latitude software or SerialEM. We have automated movie-mode drift-correction installed at the microscope. 

APPLICATION

This microscope is a great instrument to collect dose-fractionated image series of single particles. Its highly coherent 300kV electron beam together with the outstandingly low contamination rate of this instrument allows for highest-resolution data collection sessions spanning several days on the same grid.

 

In addition, the Medipix detector mounted underneath the Gatan K2-Summit direct electron detector allows for single-electron sensitive electron diffraction data collection.  

The K2-Summit DED camera can record images of up to 16 megapixels in size, or even 64 megapixels in size when using super-resolution mode. However, the K2-Summit is beam-sensitive, so that only images but not electron diffraction patterns can be recorded.

The Medipix detector, instead, offers a much smaller 1 megapixel frame, but is virtually infinitely beam resistant at 200kV, so that electron diffraction patterns can be collected. Here, the Polara is used to collect tilt-series of diffraction patterns of 3D crystals of dimensions as small as 100 nm in diameter. This still allows the Abrahams group to determine the atomic resolution structure of the molecules in the 3D crystal.