Optical n(p, T_90) measurement suite 2: H_2O and D_2O

Published

May 28, 2024

Author(s)

Patrick Egan, Yuanchao Yang

Abstract

A suite of measurements of refractive index n(p, T_90) is reported for gas phase ordinary water H_2O and heavy water D_2O. The methodology is optical refractive index gas metrology, operating at laser wavelength 633 nm and covering the range (293 < T_90 < 433) K and p < 2 kPa. A key output of the work is the determination of molar polarizabilities A_R = 3.7466(18) * [1 + 1.5(6) x 10^-6 (T/K - 303) ] cm^3/mol for ordinary water, and A_R = 3.7135(18) * [1 + 4.4(10) x 10^-6 (T/K - 303) ] cm^3/mol for heavy water, with the numbers in parentheses expressing standard uncertainty. For heavy water, this work appears to be only the second gas phase measurement to date. For both ordinary and heavy water, this work agrees within 0.15 % with recent ab initio theoretical results for A_R, but the comparison is affected by imperfect knowledge of dispersion. For ordinary water, the close agreement between the present work and theory suggests problems at the 2 % level in the low density limit of the reference formulation for refractivity.

Citation

International Journal of Thermophysics

Volume

45

Issue

6

Pub Type

Journals

Download Paper

https://doi.org/10.1007/s10765-024-03380-w

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Keywords

Water vapor, refractometry, polarizability, thermodynamic metrology

Citation

Egan, P. and Yang, Y. (2024), Optical n(p, T_90) measurement suite 2: H_2O and D_2O, International Journal of Thermophysics, [online], https://doi.org/10.1007/s10765-024-03380-w, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957560 (Accessed April 24, 2026)

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