Detection of Propane by IR-ATR in a Teflon®-Clad Fluoride Glass Optical Fiber

The detection of propane with the use of ATR spectroscopy at 3.3 µm, as the gas diffuses through the Teflon® cladding of a fluoride optical fiber, is reported. A theoretical expression for the time-dependent absorbance of the fiber sensor as a function of diffusion coefficient and cladding dimensions is developed. The experimental data fitted to the model give a diffusion coefficient of 8.85 × 10 −14 m 2 s −1 for propane in Teflon®. The potential of the technique for remote or distributed sensing of hydrocarbons is discussed.