New Concept in Helium Cooled Transmission Microscopes Philips Tecnai F30 Helium: Design and First Results

Abstract

To date it has been possible to solve the structure of several membrane proteins to atomic resolution with cryo-electron crystallography (1-4). in all studies two-dimensional crystals were required as well as special provisions on the transmission microscope. in all cases a field emission gun provided the necessary coherence and liquid-Helium cooling the specimen protection (4,5).Although repeatedly studies have been done on the cryo-protection factor of beam sensitive specimen at liquid-Nitrogen and liquid-Helium temperatures (6-10), the data available are still too limited for a clear demonstration of the superiority of liquid-Helium. Especially investigations are needed with individual particles embedded in amorphous ice (11).To meet the increasing demand for liquid-Helium cooling, FEI developed the Tecnai F30 Helium. The challenge was to provide an instrument with a very stable cryo-stage, which can work at liquid- Nitrogen as well as liquid-Helium temperature.