Low-dose performance of parallel-beam nanodiffraction

Marek Malac, Marco Beleggia, Yoshifumi Taniguchi, Ray F. Egerton, Yimei Zhu

Research output: Contribution to journalJournal articleResearchpeer-review


We evaluate the low-dose performance of parallel nano-beam diffraction (NBD) in the transmission electron microscope as a method for characterizing radiation sensitive materials at low electron irradiation dose. A criterion, analogous to Rose's, is established for detecting a diffraction spot with desired signal-to-noise ratio. Our experimental data show that a dose substantially lower than in high-resolution bright-field imaging is sufficient to determine structure and orientation of individual nanoscale objects embedded in amorphous matrix. In an instrument equipped with a cold field-emission gun it is possible to form a probe with sub-3nm diameter and sub-0.3mrad convergence angle with sufficient beam current to record a diffraction pattern with less than 0.2s acquisition time. The interpretation of NBD patterns is identical to that of selected area diffraction patterns. We illustrate the physical principles underlying good low-dose performance of NBD by means of a phase grating. The electron irradiation dose needed to detect a diffraction peak in NBD is found proportional to 1/N2, where N is the number of lattice planes contributing to the peak.
Original languageEnglish
Issue number1
Pages (from-to)14-21
Number of pages8
Publication statusPublished - 2008
Externally publishedYes


  • Electron diffraction
  • Low-dose microscopy
  • Radiation damage
  • TEM imaging
  • Phase contrast
  • Nanoparticle


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