Oxygen detection via nanoscale optical indicators

Oxygen plays a ubiquitous role in terrestrial biological processes such as respiration and chemical process, i.e. oxidation-reduction reactions. We have developed an optical technique for monitoring oxygen in both gas and liquid phases utilizing nanoscale metal-halide clusters immobilized in a porous matrix. The sensor monitors the luminescence intensity or lifetime from inorganic hexanuclear molybdenum chloride clusters (Mo₆Cl₁₂) which is efficiently quenched by ground state ³O₂. Control of the material properties of the matrix at the nanometer scale is requires for fast quantitative output from our reflection mode fiber based sensor. For aqueous applications we can monitor dissolved oxygen in the 0.2-17 mg/L range at temperatures of 10-25°C. The sensor output was validated using a commercial electro-chemical sensor and the Stern-Volmer fit is linear over the entire measurement range. In the gas phase our device can monitor oxygen with a response time, t₉₅, of 30 s in the 0.1 - 21 % range.