A DARK FIELD-TYPE SCHLIEREN MICROSCOPE FOR QUANTITATIVE, IN-SITU MAPPING OF SOLUTE CONCENTRATION PROFILES AROUND GROWING CRYSTALS

A microscope has been developed For the in situ, quantitative mapping of solute concentration profiles around growing crystals. By this opti cal instrument, which is based on a combination of the Schlieren techn ique and the dark field method, images of diffusion fields are readily obtained. The position-dependent intensity of these images is proport ional. to the local x or y gradients of solute concentration. After ca libration, video recording, digitizing and numerical integration of th e image, quantitative and detailed concentration maps are obtained. Th e viability of the method has been demonstrated by the in situ measure ment of AgNO3 diffusion fields around silver dendrites growing from aq ueous solution by electrolysis.