Cavitation as Artifact in Stopped Flow Experiments

Abstract

The time resolution of stopped flow devices is limited by the time required for homogeneous, rapid mixing. At high enough flow velocities cavitation occurs in the liquid, which at high sensitivity obscures optical detection in the early history of the reaction mixture. In a Gibson‐Milnes type stopped flow apparatus, in the flow rate range of 5–10 m sec−1, forced vortex or inertial breakdown is the major mechanism of bubble formation, depending on the way of stopping. The amplitude and lifetime of the effect are reported in pure water, methanol, and benzene as a function of mixer design, flow velocity, mixing ratio, temperature, way of stopping, as well as way of detection.