Three‐Dimensional, Molecule‐Sensitive Mapping of Structured Falling Liquid Films Using Raman Scanning

A method for molecule‐sensitive, non‐contact and marker‐free 3D mapping of vertical falling liquid films using Raman spectroscopy is presented. Technical liquid films are common in many applications in the chemical industry such as columns, evaporators, dryers and absorbers/desorbers. Measurements of an aqueous sodium sulfate film on a plain surface with a small pyramid attached to it, as well as a pillow plate are presented using a 3D surface plot. Suppressing surface gloss as well as other optical reflections from the metallic backplates is realized by using only inelastic light scattering and mathematical background correction. The results show that liquid mapping with Raman spectroscopy is possible and 3D maps can be created from different structured surfaces. This contribution presents measurements of a liquid falling film using Raman scanning. As reference substance, sodium sulfate is used and diluted in tap water. The falling film surface is structured with two example structures, a pyramid disturbance on a plain surface and a pillow plate focused on one pillow.