Molecular bending mode frequencies of the surface and interior of crystalline ice

Abstract

The Fourier transform infrared (FT-IR) spectra of the bending modes of the three categories of molecules at the surface of ice nanocrystals have been determined for both H2O and D2O samples and the response of the bending mode of the dangling hydrogen surface molecules to association with adsorbates of varying acceptor strengths has been examined. From these combined data for water molecules in a wide range of environments at the ice surface, a clear picture of the dependence of the bending mode frequency on the extent of H-bonding is revealed for ice-related conditions. These frequencies have been examined in terms of the linear equation developed by Falk that relates the water decoupled bend mode frequency to H-bond strength through the average of the symmetric and asymmetric stretch mode frequencies. The published value of 1735 cm−1, for the decoupled bend mode frequency of bulk H2O ice, is consistent with this presentation of the new data, but a new value, higher by at least 40 cm−1 than the accepted value of ∼1220 cm−1, is indicated for D2O ice. A value of 1265 cm−1 is offered as the best estimate of the bend mode frequency of D2O ice.

Ab initio study of bending modes in water cage clusters, (H2O)n, n6–10

“…The most intense features were obtained near 80 cm −1 . This value can be compared with the frequency of maximum intensity, measured at 55 cm −1 for the surface bending spectra of ice nanocrystals 33 (here the shift was calculated with respect to the experimental gaseous frequency). The three‐coordinated DDA and DAA molecules are likely to be major contributors to this surface band 32, 33.…”

“…This value can be compared with the frequency of maximum intensity, measured at 55 cm −1 for the surface bending spectra of ice nanocrystals 33 (here the shift was calculated with respect to the experimental gaseous frequency). The three‐coordinated DDA and DAA molecules are likely to be major contributors to this surface band 32, 33. The difference between the two values may be due to computational inaccuracies or to different molecular configurations in the respective systems; in clusters, three‐coordinated molecules are connected to each other, whereas in the disordered nanocrystal surface, DDA and DAA are connected to four‐coordinated molecules 20.…”

“…Finally, ref. 33 reported surface bending spectra of very large clusters (nanocrystals). A broad feature was measured extending from 1600 to about 1760 cm −1 .…”

Bovine serum albumin observed by infrared spectrometry. I. Methodology, structural investigation, and water uptake

“…In this study we concentrated on the measurement of the number of H 2 O molecules that appear in the dehydration spectra; the determination of the hydrogen‐bond configurations, which is how they bind to neighboring molecules, are analyzed in the companion study 25. One way to perform this measurement is by measuring the integrated intensity of the δ HOH band of H 2 O,4 which is not very sensitive to hydrogen bonds,45 even if it displays some variations between different phases of water 46. This integrated intensity may consequently be thought in a first approximation to be proportional to the number of H 2 O molecules.…”

Solid water clusters in the size range of tens–thousands of H2O: a combined computational/spectroscopic outlook

“…The spectra of the bending modes of the water molecules on the surface of ice particles have been investigated by combined FTIR and ab initio computations [125,154] (figure 4). The intensity of the molecular bending mode of the core and subsurface ice is very low, so the bands for the bending modes of the three types of surface water molecules, d-H, d-O and s-4, stand out clearly.…”