Liquid transmission electron microscopy (LTEM) enables researchers to observe the nucleation and growth of nanostructures in liquid media in real time. Thao Ngo and Hong Yang, University of Illinois at Urbana−Champaign, USA, reviewed several of the ways in which LTEM offers direct verification of existing theories and reveals complex, unpredicted processes.

LTEM observation of crystal formation reveals the roles played by precursor molecule adsorption, particle aggregation, and phase changes, which sometimes occur simultaneously. LTEM also enables the observation of particles near a surface spontaneously rotating and aligning themselves before attaching.

LTEM can track particle shape evolution, including the formation of faceted nanostructures, oxidative etching processes, and the effects of electron beam irradiation. Observing the growth of large crystal grains at the expense of smaller grains suggests ways to prevent this process, which decreases the crystals’ catalytic activity.

This rapidly growing area of research provides an unprecedented look at the fundamental phenomena underlying nanostructure growth and development, and it provides quantitative data for validating theories of crystal growth and self-assembly processes.

• Toward Ending the Guessing Game: Study of the Formation of Nanostructures Using In Situ Liquid Transmission Electron Microscopy,
  Thao Ngo, Hong Yang,
  J. Phys. Chem. Lett. 2015.
  DOI: 10.1021/acs.jpclett.5b02210