Infrared Spectroscopy on Equilibrated High-Density Amorphous Ice

Aigerim Karina; Tobias Eklund; Christina M Tonauer; Hailong Li; Thomas Loerting; Katrin Amann-Winkel

doi:10.1021/acs.jpclett.2c02074

Infrared Spectroscopy on Equilibrated High-Density Amorphous Ice

J Phys Chem Lett. 2022 Sep 1;13(34):7965-7971. doi: 10.1021/acs.jpclett.2c02074. Epub 2022 Aug 18.

Authors

Aigerim Karina¹, Tobias Eklund^{1

2}, Christina M Tonauer³, Hailong Li⁴, Thomas Loerting³, Katrin Amann-Winkel^{1

2

4}

Affiliations

¹ Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden.
² Institute of Physics, Johannes Gutenberg University Mainz, 55128 Mainz, Germany.
³ Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria.
⁴ Max-Planck-Institute for Polymer Research, 55128 Mainz, Germany.

Abstract

High-density (HDA) and low-density amorphous ices (LDA) are believed to be counterparts of the high- and low-density liquid phases of water, respectively. In order to better understand how the vibrational modes change during the transition between the two solid states, we present infrared spectroscopy measurements, following the change of the decoupled OD-stretch (v_OD) (∼2460 cm^-1) and OH-combinational mode (v_OH + v₂, v_OH + 2v_R) (∼5000 cm^-1). We observe a redshift from HDA to LDA, accompanied with a drastic decrease of the bandwidth. The hydrogen bonds are stronger in LDA, which is caused by a change in the coordination number and number of water molecules interstitial between the first and second hydration shell. The unusually broad uncoupled OD band also clearly distinguishes HDA from other crystalline high-pressure phases, while the shape and position of the in situ prepared LDA are comparable to those of vapor-deposited amorphous ice.