In order to understand various environmental effects of pollution, scientists tracking the movement of elements, particularly at interfaces between water and minerals.
In a new study chemists have been able to look at the interface between water and muscovite mica. A flat mineral commonly found in granite, soils and many sediments.
In the experiment, the researchers flowed a rubidium-containing solution over the mica, which caused rubidium atoms to replace the potassium that occurs naturally near the surface of the mica. Then the rubidium solution replaced for one containing sodium, which in turn replaced the rubidium atoms.
According to Argonne chemist Sang Soo Lee, the dynamics of ion transport largely controlled by electrostatic properties between mica and water. Essentially, the rubidium atoms “clung” to the mica’s surface similarly to how lint clings to clothing.
The strength of clinging behavior determined mainly by how many water molecules were in between the mica’s surface and rubidium the fewer water molecules.
Researchers used Argonne’s Advanced Photon Source, a DOE Office of Science User Facility, to observe the activity of the rubidium using a technique called resonant anomalous X-ray reflectivity. This technique allows scientists to probe the position of a single element at an interface.
By using the technique, the researchers able to condense the time frame. It takes to measure the signal from the data. Normally these data take hours to measure, but now we have a time resolution of one or two seconds.
The real-time dynamics of these kinds of interfaces give scientists a new view of how ions sense surfaces energetically.
More information: [Nature]