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Revised Formulation for the Refractive Index of Water and Steam as a Function of Wavelength, Temperature, and Density



Allan H. Harvey, J S. Gallagher, Johanna Levelt Sengers


Schiebener et al. Published a formulation for the refractive index of water and steam in this Journal in 1990. It extended over the ranges 0.2 m to 2.5 m in wavelength, 263 K to 773 K in temperature, and 0 kg m-3 to 1045 kg m-3 in density. It was based on the 1984 NBS/NRC equation of state for water and steam, and it was adopted by the International Association for the Properties of Water and Steam (IAPWS) in 1991. In the present paper, the data, after conversion to ITS-90, have been refitted by the same functional relation, but based on the newest equation of state adopted by IAPWS. The revised coefficients are reported, and a moderate amount of tabular material is provided. The revised formulation was adopted by IAPWS in 1997, and is available as part of a NIST Standard Reference Database. For most conditions, the revised formulation differs insignificantly from the previous one. A substantial improvement has been obtained, however, in supercooled water at ambient pressure, where the previous formulation was defective. Special attention has been paid to the behavior of the refractive index in the near infrared, at wavelengths up to 2.5 m, where strongly oscillating data were reported after the correlation of Schiebener et al. Had appeared, leading to subsequent curtailing of the range of validity of the formulation. Newer data in the infrared do not show these oscillations. They are compared with the revised formulation.
J. Phys. & Chem. Ref. Data (JPCRD) -
No. 4


formulation, infrared, ITS-90, molar refraction, refractive index, steam, supercooled water, supercritical steam, ultraviolet


Harvey, A. , Gallagher, J. and Levelt, J. (1998), Revised Formulation for the Refractive Index of Water and Steam as a Function of Wavelength, Temperature, and Density, J. Phys. & Chem. Ref. Data (JPCRD), National Institute of Standards and Technology, Gaithersburg, MD (Accessed July 13, 2024)


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Created July 1, 1998, Updated June 2, 2021