= Solution
\b[Use low-voltage, preferably aberration-corrected <HRTEM>, with about 60–80 kV as a defensible operating range.] An approximately 80 kV starting point balances useful lattice resolution against <carbon> displacement damage; use the lower end if the instrument still resolves the lattice and defect stability is the priority.
A higher accelerating <voltage> reduces the <electron> <wavelength>, but can remove <carbon> atoms by <knock-on displacement>. Measurements on pristine single-layer <graphene> show a strong increase in displacement probability above the vicinity of 80 kV, so simply selecting a conventional 200–300 kV setting is a poor way to preserve the original lattice.<Accurate Measurement of Electron Beam Induced Displacement Cross Sections for Single-Layer Graphene by Jannik C. Meyer and others>[Beam-energy dependence of displacement cross sections, Physical Review Letters 108, 196102]{ref}
<reduced graphene oxide> is already defective and chemically modified. Its vulnerable sites need not share the pristine-graphene threshold, and <ionization>, contamination and chemical etching remain possible at low <voltage>. Minimize dose, spread the beam while aligning and compare successive short exposures. \b[The <voltage> choice suppresses one damage mechanism; it does not guarantee damage-free imaging.]
Back to article page
