Mitigation of radiation damage in biological macromolecules via tunable picosecond pulsed transmission electron microscopy

AbstractWe report mitigation of electron-beam-induced radiation damage in biological macromolecules using rapid, low-dose transmission electron microscopy (TEM) with a new, tunable, retrofittable picosecond pulser. Damage mitigation strategies historically consisted of sample cryoprotection and ultra-low beam current; ultrafast laser-pulsed systems have shown promise, but with day-long acquisition times. We show the first practical, fast, laser-free tunable system, with acquisition of diffraction series in minutes at 5.2 GHz and 10 pA. This is the largest study to date: two materials (C36H74 paraffin and purple membrane), two beam energies (200 keV and 300 keV), two independent microscopes (Schottky and LaB6), two modes (pulsed and continuous), and unsurpassed repetition rate tunability. Critical dose at room temperature doubled versus continuous beam for ∼100 MHz single-electron repetition rates. Results herald a new class of highly-tunable, ultrafast pulsers with future applications in cryogenic electron microscopy (CryoEM), high resolution single particle imaging, and rapid low-dose TEM.

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Detection efficiency and estimation of the performance of high voltage STEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107563 ◽

1978 ◽

Vol 36 (1) ◽

pp. 84-85

Author(s):

A. Ishikawa ◽

C. Morita ◽

M. Hibino ◽

S. Maruse

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Radiation Damage ◽

High Voltage ◽

Detection Efficiency ◽

Beam Current ◽

High Energy ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

Transmission Electron

One of the problems which are met in conventional transmission electron microscopy (CTEM) at high voltages is the reduction of the sensitivity of photographic films for high energy electron beams, resulting in the necessity of using high beam current. This cancels out an advantage of high voltage electron microscopy which is otherwise expected from the reduction of the inelastic scattering in the specimen, that is the reduced radiation damage of the specimen during observations. However, it is expected that the efficiency of the detector of scanning transmission electron microscopy (STEM) can be superior to that of CTEM, since the divergence of the electron beam in the detecting material does not affect the quality of the image. In addition to observation with less radiation damage, high voltage STEM with high detection efficiency is very attractive for observations of weak contrast objects since the enhancement of the contrast (which is an important advantage of STEM) is easily realized electrically.

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Annealing Of Radiation Damage in Tungsten

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069053 ◽

1970 ◽

Vol 28 ◽

pp. 412-413

Author(s):

Robert C. Rau ◽

John Moteff

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Radiation Damage ◽

Thermal Annealing ◽

Neutron Fluence ◽

Dislocation Loops ◽

Defect Clusters ◽

Polycrystalline Tungsten ◽

Transmission Electron ◽

Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

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