Film Growth of Ice by Vapor Deposition at 128−185 K Studied by Fourier Transform Infrared Reflection−Absorption Spectroscopy:  Evolution of the OH Stretch and the Dangling Bond with Film Thickness

Abstract

The polycrystalline and noncrystalline ice films vapor-deposited at 128-185 K were investigated by grazingangle Fourier transform Infrared Reflection-Absorption Spectroscopy (RAS). In particular, the polycrystalline ice phase was found above 155 K, whereas the noncrystalline phase was formed below 145 K. The nature of the polycrystalline and noncrystalline ice phases can be differentiated by comparing the respective RA spectra with spectral simulations based on the Fresnel reflection and Mie scattering methods. Furthermore, the OH stretching band (3800-2800 cm -1 ) exhibits complex behavior as a function of film thickness (from less than 10 nm to 1500 nm), which can be simulated and attributed primarily to the physics of absorption-reflection based on the Fresnel equations for reflection coefficients for parallel-and perpendicular-polarized light in a vacuum-dielectric film-metal system. The spectral evolution of the OH stretch with the film thickness is found to be similar for both polycrystalline and noncrystalline phases. In addition, spectral features of the incompletely coordinated OH groups at 3700-3690 cm -1 have been observed for a majority of noncrystalline and polycrystalline ice samples grown under different conditions (e.g., at 185 K), which shows that these OH dangling bonds are an integral part of the surfaces of both noncrystalline and polycrystalline ice phases. For thin films less than 200 nm thick, both kinds of ice are found to have a comparable amount of OH dangling bonds. In contrast, the thicker films (with thicknesses greater than 700 nm) of the noncrystalline phase contain a noticeably larger amount of OH dangling bonds than the polycrystalline films of comparable thickness. This thickness dependence of the OH dangling bond feature suggests that the OH dangling bonds are located most likely on the external surfaces of the crystalline grains and/or of the ice film itself at larger thicknesses for polycrystalline phase and on the tracery external surface in the case of noncrystalline phase.

Extent and relevance of stacking disorder in “ice Ic”

“…From our diffraction studies we now find that significant amounts of amorphous phase are unlikely to exist in contact with "ice I c "; earlier evidence for amorphous relics in "ice I c ", based on a simplified analysis of low-resolution diffraction data (16,39,43), should be reconsidered in the light of an appropriate model for stacking disorder and with higher-resolution data, in line with the conclusions of Mitlin and Leung (53). The situation may, however, be different for solutes at high concentration, which impede or even prevent any water crystallization at temperatures even far below the melting point (55).…”

On the State of Water Ice on Saturn’s Moon Titan and Implications to Icy Bodies in the Outer Solar System

“…Here, we assign it to the stretching of the dangling OH bond coupled with the bending of the water molecules. 31 The existence of the dangling OH bonds suggests that the water ice deposited at 10 K was porous amorphous ice. We warmed up the amorphous ice from 10 K to 50 K at a speed of 0.5 K min -1 .…”

Thermal Evolution of Acetic Acid Nanodeposits over 123−180 K on Noncrystalline Ice and Polycrystalline Ice Studied by FTIR Reflection−Absorption Spectroscopy: Hydrogen-bonding Interactions in Acetic Acid and between Acetic Acid and Ice

“…The thickness of the ice film was estimated by using a procedure based on the Fresnel method, which has been given in detail in our previous work. 25 Figure 1a shows the FTIR-RA spectrum of an ice film deposited at 5.0 × 10 -7 Torr for 900 s at 123 K, which is estimated to have a film thickness of ∼6 nm from the Fresnel analysis. 25 Evidently, the spectrum is dominated by a strong broad band at 3376 cm -1 and a weaker feature at 1656 cm -1 , corresponding to the OH stretching modes and the HOH bending mode of the bulk, respectively.…”

“…25 Figure 1a shows the FTIR-RA spectrum of an ice film deposited at 5.0 × 10 -7 Torr for 900 s at 123 K, which is estimated to have a film thickness of ∼6 nm from the Fresnel analysis. 25 Evidently, the spectrum is dominated by a strong broad band at 3376 cm -1 and a weaker feature at 1656 cm -1 , corresponding to the OH stretching modes and the HOH bending mode of the bulk, respectively. Furthermore, a sharp but considerably weaker feature at 3696 cm -1 can also be observed, which can be attributed to the OH dangling-bond mode, i.e., the OH stretching mode for which the H atom is not involved in the H-bonding.…”