High temperature optical fiber oxygen probe

We report on the development of an optical sensor suitable for remote monitoring of oxygen in high temperature environments. The sensor is based on ³O₂ quenching of the red emission from hexanuclear molybdenum chloride clusters. A reflection mode fiber optic probe is being developed by immobilizing Mo₆Cl₁₂ in a porous sol-gel matrix at the far end of a high temperature silica fiber. The sensor signal as a function of temperature was determined from in-situ spectroscopic measurements, demonstrating operation up to at least 200°C. One of the advantages of the inorganic Mo-cluster is the lack of sensitivity to gases typically present in a coal-fired boiler due to the triplet nature of the transition from the excited to ground state.