Fluorescent imaging agents for mapping temperature field and capillary flow on the surface of volatile solvent

The understanding of thermocapillary convection is important in both fundamental and industrial aspects. However, efficient tools that can provide dynamic details of the convective flows are still lacking. Here, we discovered a unique phenomenon of photoinduced fluorogenic shift of HDPI derivatives in chloroform and utilized this trait to map the temperature field and capillary flow on the surface of or inside volatile chloroform with a high spatial resolution and a long observation window. By inducing a proper co-imaging agent that enhanced the fluorescence contrast via generating more distinguishable chromaticity, the fluorescence-based method exhibited further enhanced imaging resolution and elongated observation time, facilitating the continuous monitoring of temperature field and capillary flow. This work presents a powerful tool to study the behaviors of fluid (thermo-)dynamics.