Cavitating Flow Luminescence as a Potential Source for Analytical Spectroscopy

Cavitating flow luminescence (CFL) has been observed for the first time at the microscale in fluid flow through a Venturi orifice. Water and mixtures of dimethyl sulfoxide and water were pumped through a Venturi orifice with a 220-mu m inside diameter at flow rates between 60-100 mL min(-1) to generate cavitation bubbles downstream of the Venturi restriction. Cavitation inception was observed to occur at a flow rate of 35 mL min(-1) and a cavitation inception number of sigma(i) approximate to 0.83. The onset of CFL emission occurred at a flow rate of 60 mL min(-1) and increased with increasing flow rate through the orifice. CFL also increased with decreasing temperature and decreasing vapor pressure of the cavitating fluid. The intensity of CFL also increased when argon was present as a dissolved gas compared to untreated fluids.