• Number 315  |
• July 6, 2010

New energy research under the microscope

Scientists can now peer into the inner workings of catalyst nanoparticles 3,000 times smaller than a human hair within nanoseconds.

The findings point the way toward future work that could greatly improve catalyst efficiency in a variety of processes that are crucial to the world’s energy security, such as petroleum catalysis and catalyst-based nanomaterial growth for next-generation rechargeable batteries.

Using a new imaging technique on the Dynamic Transmission Electron Microscope (DTEM), at DOE's Lawrence Livermore’s National Laboratory, researchers have achieved unprecedented spatial and temporal resolution in single-shot images of nanoparticulate catalysts.

The DTEM uses a laser-driven photocathode to produce short pulses of electrons capable of recording electron micrographs with 15-nanosecond (one billionth of a second) exposure time. The recent addition of an annular dark field (ADF) aperture to the instrument has greatly improved the ability to time-resolve images of nanoparticles as small as 30 nanometers in diameter.

“Nanoparticles in this size range are of crucial importance to a wide variety of catalytic processes of keen interest to energy and nanotechnology researchers,” said UC Davis’ Dan Masiel, formerly of LLNL and lead author of a paper appearing in the journal, ChemPhysChem. “Time-resolved imaging of such materials will allow for unprecedented insight into the dynamics of their behavior.”

Previously, particles smaller than 50 nanometers could not be resolved in the 15-nanosecond exposure because of the limited signal and low contrast without ADF aperature. But by using DTEM’s ADF, almost every 50-nanometer particle and many 30-nanometer ones became clearly visible because of the fast time resolution and improved contrast.

[Anne Stark, 925.422.9799,
stark8@llnl.gov]