Temperature-dependent optical constants of water ice in the near infrared:new results and critical review of the available measurements

The optical constants of water ice have been determined in the near infrare d from 4000 to 7000 cm(-1). Polycrystalline ice films with thickness as gre at as similar to 1164 mum were formed by condensation of water vapor on a c old silicon substrate at temperatures of 166, 176, 186, and 196 K. The tran smission of light through the ice films was measured during their growth fr om 0 to 1164 pm over the frequency range of approximately 500-7000cm(-1). T he optical constants were extracted by means of simultaneously fitting the calculated transmission spectra of films of varying thickness to their resp ective measured transmission spectra with an iterative Kramers-Kronig techn ique. Equations are presented to account for reflection losses at the inter faces when the sample is held in a cell. These equations are used to reanal yze the transmission spectrum of water ice (358-mum sample at 247 K) record ed by Ockman in 1957 [Philos. Mag. Suppl. 7, 199 (1958)]. Our imaginary ind ices for water ice are compared with those of Gosse et al. [Appl. Opt. 34, 6582 (1995)], Kou et al. [Appl. Opt. 32, 3531 (1993)], Grundy and Schmitt [ J. Geophys. Res. 103, 25809 (1998)], and Warren [Appl. Opt. 23, 1206 (1984) ], and with the new indices from Ockman's spectrum. The temperature depende nce in the imaginary index of refraction observed by us between 166 and 196 K and that between our data at 196 K and the data of Gosse et al. at 250 K are compared with that predicted by the model of Grundy and Schmitt. On th e basis of this comparison a linear interpolation of the imaginary indices of refraction between 196 and 250 K is proposed. We believe that the accura cy of this interpolation is better than 20%. (C) 2001 Optical Society of Am erica.