High-Resolution Optical Microscopy of Gas Hydrates
Résumé
This chapter reviews high‐resolution optical microscopy methods and highlights their value for gas hydrate research with examples addressing a model hydrate system, cyclopentane hydrate. It illustrates the potential and complementarity of various imaging modes including differential interference contrast (DIC), dark field, fluorescence and (confocal) reflection. These modes are readily available in modern, infinity‐corrected optical microscopes. The chapter also illustrates the potential of Brewster angle microscopy for precise imaging of lateral heterogeneities on a planar surface. Based on Brewster angle microscopy observations, the chapter argues that nonuniform (or “patchy”) polymer adsorption is responsible for these two apparently contradictory phenomena — inhibition of gas hydrate formation and enhanced stability of the formed hydrate. The proposed mechanism is similar to that proposed in the literature for explaining both why anti‐freeze proteins (AFPs) stop ice growth at T well below 0 °C and why ice crystals melt at temperatures significantly above 0 °C up to ~0.5 °C.