Scientists Develop High-Pressure Enabled Atomic Force Microscope to Study Geochemical Processes

It is a challenging task to study the behavior of CO₂ with instruments under geological conditions involving high-pressure. A new atomic force microscope (AFM) was developed by scientists at Lawrence Berkeley National Laboratory, Wright State University  and Pacific Northwest National Laboratory to withstand the pressure encountered by stored  greenhouse gases underground.

Scientists can view images and movies of reactions as and when they take place under similar conditions as at a carbon sequestration site using the new AFM. Removing CO₂ from industrial emissions and accumulating it underground enables researchers to give answers to some basic questions such as the interaction of carbon dioxide with adjacent mineral surfaces. The new device provides the required answers.

CO₂ is injected into porous rocks present underground at a distance of more than half a mile below the surface, where the pressure and temperature conditions are favorable to sustain CO₂ in a supercritical fluid state. At this state, CO₂ exhibits both liquid and gaseous properties. Researchers wanted to observe a real time viewing of the reactions taking place under native environmental conditions. The chemical interactions between minerals present in rock formations and supercritical CO₂ could be understood better with the help of the images.

The researchers designed an apparatus to enable an atomic force microscope to withstand temperatures approximately up to 350°K and pressures of 100 atm. Scientists used this microscope to produce images and a real-time film of the reaction of supercritical CO₂ with a hydrated calcite surface. Calcite surfaces are easy to prepare and they can be used for AFM studies. It can also be used to observe other chemical reactions taking place at high pressures.