EPFL researchers have developed an optical imaging tool to visualize surface chemistry in real time. They imaged the interfacial chemistry in the microscopically confined geometry of a simple glass micro-capillary. The glass is covered with hydroxyl (-OH) groups that can lose a proton – a much-studied chemical reaction that is important in geology, chemistry and technology. A 100-micron long capillary displayed a remarkable spread in surface OH bond dissociation constant of a factor of a billion. The research has been published in Science.