A dark field-type Schlieren microscope for quantitative, in situ mapping of solute concentration profiles around growing crystals

Abstract

A microscope has been developed for the in situ, quantitative mapping of solute concentration profiles around growing crystals. By this optical instrument, which is based on a combination of the Schlieren technique and the dark field method, images of diffusion fields are readily obtained. The position-dependent intensity of these images is proportional to the local x or y gradients of solute concentration. After calibration, video recording, digitizing and numerical integration of the image, quantitative and detailed concentration maps are obtained. The viability of the method has been demonstrated by the in situ measurement of AgNO3 diffusion fields around silver dendrites growing from aqueous solution by electrolysis.