Far-infrared absorption in liquid water

• Published in: Chemical physics letters 1985-01, Vol.118 (6), p.622-625
• Main Authors: Hasted, J.B., Husain, S.K., Frescura, F.A.M., Birch, J.R.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/0009-2614(85)85366-5

The results of new measurements of the far-infrared optical constants of liquid water out to 4 cm −1 at 293 K are presented. These, together with previously published submillimetre wavelength measurements, are analysed to show that it is possible to fit the continuous far-infrared-to-microwave absorption spectrum to classical polar-molecule relaxation theory with added contributions from Gaussian oscillators close to 200 and 50 cm −1. Both of these oscillators have been observed in Raman studies. The 200 cm −1 band is well characterised in infrared measurements, but the present work represents the first unambiguous identification of the 50 cm −1 band in infrared observations.