Reversible and Selective Fiver Optic Hydrazine Vapor Detector

This proposed program is directed towards the development and subsequent evaluation of a distributed multi-site fiber optic chemical sensor for real time monitoring of unsymmetrical dimethylhydrazine (UDMH) and its congeners monomethylhydrazine (MMH) and hydrazine (H) for concentration to 10ppb. Proposed fiber optic chemical sensor technology relies upon the reversible chemical bleaching of selected immobilized triphenylmethane dyes. Hydrazine related vapors (UDMH, MMH and H) will react with the central carbon of triphenylmethane dyes reversibly forming Lewis acid-base abducts. Formation of these abducts will result in chemical bleaching of initially intensely colored dyes to give, upon complete saturation, colorless intermediates. Subsequent removal of hydrazine related species will shift the equilibrium back to the free triphenylmethane dye coated optical fibers will induce an optical change in both the dye and at the dye-optical fiber interface. This will give a detectable perturbation at the evanescent wave being transmitted through the optical fiber.