Thursday, October 2, 2008
2008 R&D 100 Winner
Many materials and biological processes occur far too quickly for a high-end microscope to witness, let alone the human eye. Observation of these phenomena, which can occur under extreme temperature and applied pressure, requires a tool like the Dynamic Transmission Electron Microscope (DTEM), which has been created jointly by Lawrence Livermore National Laboratory (LLNL), Livermore, Calif., and JEOL USA, Inc., Peabody, Mass. The DTEM captures images with a high spatial resolution of less than 10 nm, using a laser-driven electron source to produce an extremely brief but intense pulse of 109 electrons.
The DTEM works by irradiating a photocathode source with a pulsed ultraviolet laser that produces photon energy greater than the target’s work function. A flux of photo-emitted electrons is produced with about the same time duration as the laser pulse, and this packet is processed in the traditional way. An arbitrary waveform generator, also developed at LLNL, can be tuned to create temporally-shaped pulses that determine the timescale for observation.Images are obtained by a single-electron-sensitive CCD camera at the same time resolution as the pulse duration, or about 15 ns.
Technology
Transmission electron microscope
Developers
Lawrence Livermore National Laboratory
JEOL USA, Inc.
