Iron reduction is particularly important for the mobility of contaminants in the environment. Because many contaminants, most notably uranium, bind to iron, the change also can affect the spread of these contaminants. A soluble form of iron will help spread the contamination while iron with larger particles can be used to trap contaminants in filter systems. Knowledge of how fast iron oxides undergo reaction and dissolution controlled in part by the electron hopping rates will help the management of some contaminant remediation efforts.
"We believe that this work is the starting point for a new area of time-resolved geochemistry," said Benjamin Gilbert, a scientist at LBNL. "Time-resolved science seeks to understand chemical reaction mechanisms by making various kinds of "movies" that depict in real time how atoms and electrons move during reactions. We have imported some of these ideas and approaches into geochemistry, and are very excited about the future possibilities."
The research team detailed their findings and how they made these "movies" in a paper "Electron Small Polarons and Their Mobility in Iron (Oxyhdr)oxide Nanoparticles" published Sept. 6 in the journal Science.
Electron transfer was only made viewable by recent advances in light source technology that allow scientists to take a quick succession of pictures to track the action of the electron traveling through the iron oxide. The journey takes pico-to-nano-seconds, depending on temperature and the structure of the iron oxide.
"Much like a sports photographer must use a camera with a very fast shutter speed to capture an athlete in motion without blurring, to be able to watch electrons moving, we needed to use a exceedingly short and very bright (powerful) pulse of X-rays," said Jordan Katz, the lead author on the Science paper, formerly of LBNL and now a scientist at Denison University. "For th
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DOE/Argonne National Laboratory