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DTSTAMP:20260405T162348Z
UID:1715158800@ist.ac.at
DTSTART:20240508T110000
DTEND:20240508T120000
DESCRIPTION:Speaker: Petar N. Petrov\nhosted by Mikhail Lemeshko\nAbstract:
  Cryo-electron microscopy can visualize biomolecules at high resolution in
  a near-native state\, but the technique is limited by the low contrast of
  specimens together with their sensitivity to electron radiation. To maxim
 ize image contrast\, a phase plate can be employed to apply an additional 
 delay between the scattered and unscattered beams in a diffraction plane o
 f the microscope. While this approach is widely used in optical microscopy
 \, phase plates developed for electron microscopy have been prone to being
  charged by or scattering the electron beam\, leading to unstable behavior
  and resolution loss. To overcome these limitations\, we have developed a 
 laser-based phase plate (LPP). A laser beam\, amplified and focused by a F
 abry-Perot optical cavity\, intersects the unscattered electron beam to im
 part the desired phase shift. The LPP provides a stable phase shift over h
 ours while keeping material objects far from the electron beam path to avo
 id scattering and decoherence. The reliability of the LPP paves the way fo
 r several future directions in cryo-electron microscopy and tomography. Im
 proved contrast at low spatial frequencies enables detection of small part
 icles inaccessible to conventional (defocus-based) phase contrast imaging\
 , as well as superior correction of beam-induced motions. Additionally\, t
 he LPP eliminates the need for specimen defocus and\, in combination with 
 a spherical aberration corrector\, permits near-perfect contrast transfer 
 over many orders of magnitude in resolution (from ~100 nm to 0.1 nm). Simu
 ltaneous visualization of both small and large structural features promise
 s to benefit cryo-electron tomography by providing high-resolution informa
 tion together with larger-scale context. I will show our progress on singl
 e-particle reconstructions and tomography with the LPP and discuss prospec
 ts for the new imaging modalities enabled by the LPP based on a combinatio
 n of experiments and simulations.
LOCATION:Moonstone Building\, Seminar Room C\, ISTA
ORGANIZER:omerhalil.unal@ist.ac.at
SUMMARY:Petar N. Petrov: Cryo-electron microscopy with a laser phase plate
URL:https://talks-calendar.ista.ac.at/events/4961
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