Infrared Intensities of Liquids XX: The Intensity of the OH Stretching Band of Liquid Water Revisited, and the Best Current Values of the Optical Constants of H2O(l) at 25°C between 15,000 and 1 cm−1

The previously reported nonreproducibility of the intensity of the OH stretching band of liquid water has been explored. It was found that it can be eliminated in measurements with the Circle® multiple ATR cell by ensuring that the ATR rod is coaxial with the glass liquid holder. It was also found that normal laboratory temperature variations of a few degrees change the intensity by ⩽∼1% of the peak height. A new imaginary refractive index spectrum of water has been determined between 4000 and 700 cm1 as the average of spectra calculated from ATR spectra recorded by four workers in our laboratory over the past seven years. It was obtained under experimental and computational conditions superior to those used previously, but is only marginally different from the spectra reported in 1989. In particular, the integrated intensities of the fundamentals are not changed significantly from those reported in 1989. The available imaginary refractive index, k, values between 15,000 and 1 cm−1 have been compared. The values that are judged to be the most reliable have been combined into a recommended k spectrum of H2O(l) at 25 °C between 15,000 and 1 cm−1, from which the real refractive index spectrum has been calculated by Kramers–Kronig transformation. The recommended values of the real and imaginary refractive indices and molar absorption coefficients of liquid water at 25 ± 1 °C are presented in graphs and tables. The real and imaginary dielectric constants and the real and imaginary molar polarizabilities in this wavenumber range can be calculated from the tables. Conservatively estimated probable errors of the recommended k values are given. The precision with which the values can be measured in one laboratory and the relative errors between regions are, of course, far smaller than these probable errors. The recommended k values should be of considerable value as interim standard intensities of liquid water, which will facilitate the transfer of intensities between laboratories.

[1]  L. Kou,et al.  Refractive indices of water and ice in the 0.65- to 2.5-µm spectral range. , 1993, Applied optics.

[2]  Y. Maréchal.  Infrared spectra of water. I. Effect of temperature and of H/D isotopic dilution , 1991 .

[3]  J. Bertie,et al.  Infrared Intensities of Liquids I: Determination of Infrared Optical and Dielectric Constants by FT-IR Using the CIRCLE ATR Cell , 1985 .

[4]  M. Querry,et al.  Optical Constants of Water in the Infrared , 1971 .

[5]  Dudley A. Williams,et al.  Lambert Absorption Coefficients of Water in the Infrared , 1971 .

[6]  P. P. Sethna,et al.  Optical constants of water in the infrared: Influence of temperature* , 1977 .

[7]  Shuliang L. Zhang,et al.  Infrared Intensities of Liquids X: Accuracy of Current Methods of Obtaining Optical Constants from Multiple Attenuated Total Reflection Measurements Using the CIRCLE Cell , 1992 .

[8]  John E. Bertie,et al.  Infrared Intensities of Liquids XI: Infrared Refractive Indices from 8000 to 2 cm−1, Absolute Integrated Intensities, and Dipole Moment Derivatives of Methanol at 25°C , 1993 .

[9]  J. Gaffney,et al.  Lambert absorption coefficients of water in the frequency range of 3000-934 cm(-1). , 1994, Applied optics.

[10]  Dudley A. Williams,et al.  Optical properties of water in the near infrared. , 1974 .

[11]  Dudley A. Williams,et al.  Far-Infrared Spectrum of Liquid Water* , 1966 .

[12]  M. N. Afsar,et al.  Measurements of the optical constants of liquid H 2 O and D 2 O between 6 and 450 cm −1 , 1977 .

[13]  R. Jones,et al.  The Control of Errors in Infrared Spectrophotometry. VI. The Evaluation of Optical Constants by Combined Transmission and Attenuated Total Reflection Measurements , 1980 .

[14]  M. K. Ahmed,et al.  Infrared intensities of liquids. 5. Optical and dielectric constants, integrated intensities, and dipole moment derivatives of water and water-d2 at 22.degree.C , 1989 .

[15]  R. Jones,et al.  Infrared Intensities of Liquids XVIII: Accurate Optical Constants and Molar Absorption Coefficients between 6500 and 800 cm−1 of Dichloromethane at 25°C, from Spectra Recorded in Several Laboratories , 1993 .

[16]  John E. Bertie,et al.  Infrared intensities of liquids XVI. Accurate determination of molecular band intensities from infrared refractive index and dielectric constant spectra , 1994 .

[17]  M. N. Afsar,et al.  Submillimetre wave measurements of optical constants of water at various temperatures , 1978 .

[18]  R. Jones,et al.  Compact Table for the Publication of Infrared Spectra That are Quantitative on Both Intensity and Wavenumber Axes , 1993 .

[19]  G. M. Hale,et al.  Optical Constants of Water in the 200-nm to 200-microm Wavelength Region. , 1973, Applied optics.

[20]  Hans R. Zelsmann,et al.  Temperature dependence of the optical constants for liquid H2O and D2O in the far IR region , 1995 .

[21]  Shuliang L. Zhang,et al.  Infrared Intensities of Liquids XV: Infrared Refractive Indices from 8000 to 350 cm−1, Absolute Integrated Intensities, Transition Moments, and Dipole Moment Derivatives of Methanol-d, at 25°C , 1994 .

[22]  G. M. Hale,et al.  Influence of Temperature on the Spectrum of Water , 1972 .

[23]  W. Luck,et al.  H-bonds in methanol—water mixtures: indications of non-H-bonded OH in liquid water , 1988 .

[24]  Udo Kaatze,et al.  The Dielectric Properties of Water at Microwave Frequencies , 1981 .

[25]  John E. Bertie,et al.  The refractive index of colorless liquids in the visible and infrared: Contributions from the absorption of infrared and ultraviolet radiation and the electronic molar polarizability below 20 500 cm−1 , 1995 .

[26]  Dudley H. Williams,et al.  Optical constants of water in the infrared , 1975 .

[27]  J. Hasted,et al.  Far-infrared absorption in liquid water , 1985 .

[28]  John E. Bertie,et al.  Measurement and use of absolute infrared absorption intensities of neat liquids , 1995 .

[29]  H. Heise,et al.  Investigation of experimental errors in the quantitative analysis of glucose in human blood plasma by ATR-IR spectroscopy , 1995 .