Rhodamine-based caged dye for aqueous MTV with green lasers

Molecular tagging velocimetry (MTV) is a nonintrusive optical diagnostic with typically three variants in liquids distinguished by the dye that they rely on: phosphorescent, photochromic, or caged. The latter scheme, initially called photo-activated nonintrusive tracking of molecular motion (PHANTOMM), required both a UV and a dedicated blue laser. Here, we demonstrate caged-dye-based MTV with pulsed UV and green lasers for the first time, simplifying its deployment in most experimental fluid dynamics laboratories.