Date: Wednesday, 31st August, 2022
Time: 10.00am (AEST)
Zoom ID: 265 224 4052
In cryogenic single-particle electron microscopy (cryo-EM) and tomography (cryo-ET), a phase plate can provide optimum image contrast for weak-phase objects. We have demonstrated a laser phase plate (LPP), based on coherently manipulating the electron wave function with a continuous laser beam, which is built up to an intensity of ~ 400 GW/cm2 by resonance in a Fabry-Perot cavity. Initial work obtained a highresolution map of 20S proteasome particles and demonstrated both the long-term stability of the LPP during data collection and the high contrast of images. We will report on how a new version, with an enlarged hole for the electron beam, overcomes the recently-discovered limitation on the resolution arising from thermal (Johnson-noise) currents in the LPP, and how installing a gun monochromator to reduce the electron-beam energy spread will overcome chromatic aberration as a limit on the resolution. In addition, we will begin working with a microscope equipped with a Cs corrector, in addition to a gun monochromator. This microscope will also feature a post-column energy filter as well as an improved camera and make use of a newly designed dual LPP with crossed laser beams, which we expect to suppress the weak ghostimages observed with a single LPP.
Holger Müller successfully applied for his first patent when he was 14. Later, he did his undergraduate thesis with Jürgen Mlynek at the University of Konstanz, Germany. He graduated from Humboldt-University, Berlin, with Achim Peters as his advisor. Müller received a fellowship of the Alexander von Humboldt foundation and joined the group of Steven Chu in Stanford as a postdoc. In July 2008, he joined the physics faculty at U.C. Berkeley.