Dynamic Transmission Electron Microscope

National Laboratory: 
Lawrence Livermore National Laboratory
Characterization Class: 
Microscopy
Description: 

The Dynamic Transmission Electron Microscope, or DTEM, is a unique in situ electron microscope at Lawrence Livermore National Laboratory that is designed to observe fast materials processes at the micro- to nano-scale. Relative to a conventional transmission electron microscopy (TEM), the DTEM platform has been augmented by the addition of two pulsed laser systems—one laser directed toward the specimen to initiate a process via laser heating and one directed to a photocathode that replaces the standard thermionic emission source in the electron gun. These systems enable time-resolved experiments with nanometer and nanosecond spatial and temporal resolutions. The DTEM’s high temporal resolution is achieved by laser-induced photoemission, generating short electron pulses for imaging and diffraction. The DTEM now operates in movie-mode, allowing user-defined electron pulse trains of up to nine pulses with precise temporal duration, shape, and spacing using an arbitrary waveform generation (AWG) laser. The electron-pulse duration can vary from tens of nanoseconds to ~1 µs. An electrostatic deflector installed beneath the electron optics in the TEM column shifts each image to a different region of the CCD detector, allowing acquisition of nine-frame movies.

Capability Bounds: 

Samples must fit into a standard TEM holder (typically 3-mm discs). There must be with an electron-transparent region of the sample where analysis will be conducted.

Unique Aspects: 

DTEM provides the ability to image transient, non-equilibrium behavior and microstructure evolution with unprecedented spatial and temporal resolution.

Availability: 

Available to members of the DTEM group and collaborators (both within and external to LLNL).

Single Point of Contact: 

Name: Joseph McKeown
Email: mckeown3@llnl.gov
Phone: 925-422-1708

References: 
  1. J.T. McKeown, Y. Wu, J.D. Fowlkes, P.D. Rack, and G.H. Campbell, “Simultaneous in-situ synthesis and characterization of Co@Cu core-shell nanoparticle arrays,” Advanced Materials 27 [6] (2015) 1060-65.
  2. G.H. Campbell, J.T. McKeown, and M.K. Santala, “Time-resolved electron microscopy for in situ experiments,” Applied Physics Reviews 1 (2014) 041101.
  3. J.T. McKeown, A.K. Kulovits, C. Liu, K. Zweiacker, B.W. Reed, T. LaGrange, J.M.K. Wiezorek, and G.H. Campbell, “In situ transmission electron microscopy of crystal growth-mode transitions during rapid solidification of a hypoeutectic Al-Cu alloy,” Acta Materialia 65 (2014) 56-68.
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