A cryo-electron microscope operating at produces electrons of wavelength

PHYSICS · Subjective · Fermi University Physics · Optics & Photonics · Biophysics & Medical Physics · Macromolecules, membranes and cell architecture

Forces, Machines and Signals, Ch Seeing molecules: diffraction, cryo-electron microscopy and fluorescence

Problem

A cryo-electron microscope operating at

200\,\mathrm{kV}

produces electrons of wavelength

\lambda = 2.51\,\mathrm{pm}

. The first zero of the contrast transfer function is to fall at a real-space spacing

d = 1/q = 2.0\,\mathrm{nm}

. Using

q = 1/\sqrt{\lambda\Delta f}

for that first zero (ignoring spherical aberration), find the defocus

\Delta f

that places it there.