Infrared Band Strengths and Optical Constants of D₂O Ices, with New Measurements on H₂O Ices and a Band-Strength Estimate for HDO

Abstract

The infrared band strengths of D₂O and H₂O ices have been calculated from new spectra at 10, 70, and 155 K. In contrast to nearly all previous work, integration ranges are provided and close attention has been paid to the use of multiple ice samples and Beer’s Law (Beer–Lambert) plots to support the claim of a linear trend of band intensity with ice thickness. Optical constants have been calculated as averages from the results of multiple measurements, in what again seems to be the first such approach for water ices. A 200% discrepancy in H₂O optical constants in the literature is addressed and a resolution suggested. The new infrared intensity results for D₂O-ice are the first in many years and are compared to previous work from almost a half-century ago. The same new results are used to estimate the intensity of the O–D stretching mode of HDO in ices at 10 K, without the need for warming to higher temperatures. The new estimate can be used for calculating HDO abundances from ice observations made with the James Webb Space Telescope.