Investigation of hydrodynamic cavitation induced reactive oxygen species production in microchannels via chemiluminescent luminol oxidation reactions

•Contactless, in situ chemiluminescence-based radical quantification.•Radical generation in micro convergent-divergent channels.•Geometry and flow parameters in micro-milli transition scale examined.•Dominant radical yielding vapor structures identified by single photon counting.•The cavitation cloud collapse was found not to be the source of the chemical yield.