Abstract
We present experimental and simulated 2D IR spectra of some high-pressure forms of isotope-pure D2O ice and compare the results to those of ice Ih published previously [F. Perakis and P. Hamm, Phys. Chem. Chem. Phys. 14, 6250 (2012); L. Shi et al., ibid. 18, 3772 (2016)]. Ice II, ice V, and ice XIII have been chosen for this study, since this selection covers many aspects of the polymorphism of ice. That is, ice II is a hydrogen-ordered phase of ice, in contrast to ice Ih, while ice V and ice XIII are a hydrogen-disordered/ordered couple that shares essentially the same oxygen structure and hydrogen-bonded network. For the transmission 2D IR spectroscopy, a novel method had to be developed for the preparation of ultrathin films (1-2 mu m) of high-pressure ices with good optical quality. We also simulated 2D IR spectra based on molecular dynamics simulations connected to a vibrational exciton picture. These simulations agree with the experimental results in a semi-quantitative manner for ice II, while the same approach failed for ice V and ice XIII. From the perspective of 2D IR spectroscopy, ice II appears to be more inhomogeneously broadened than ice Ih, despite its hydrogen-order, which we attribute to the fact that ice II is structurally more complex with four distinguishable hydrogen bonds that mix due to exciton coupling. Ice V and ice XIII, on the other hand, behave as expected with the hydrogen-disordered case (ice V) being more inhomogenously broadened. Furthermore, in all hydrogen-ordered forms (ice II and ice XIII), cross peaks could be identified in the anisotropic 2D IR spectrum, whose signs reveal the relative direction of the corresponding excitonic states. Published by AIP Publishing.
Abstract
We present experimental and simulated 2D IR spectra of some high-pressure forms of isotope-pure D2O ice and compare the results to those of ice Ih published previously [F. Perakis and P. Hamm, Phys. Chem. Chem. Phys. 14, 6250 (2012); L. Shi et al., ibid. 18, 3772 (2016)]. Ice II, ice V, and ice XIII have been chosen for this study, since this selection covers many aspects of the polymorphism of ice. That is, ice II is a hydrogen-ordered phase of ice, in contrast to ice Ih, while ice V and ice XIII are a hydrogen-disordered/ordered couple that shares essentially the same oxygen structure and hydrogen-bonded network. For the transmission 2D IR spectroscopy, a novel method had to be developed for the preparation of ultrathin films (1-2 mu m) of high-pressure ices with good optical quality. We also simulated 2D IR spectra based on molecular dynamics simulations connected to a vibrational exciton picture. These simulations agree with the experimental results in a semi-quantitative manner for ice II, while the same approach failed for ice V and ice XIII. From the perspective of 2D IR spectroscopy, ice II appears to be more inhomogeneously broadened than ice Ih, despite its hydrogen-order, which we attribute to the fact that ice II is structurally more complex with four distinguishable hydrogen bonds that mix due to exciton coupling. Ice V and ice XIII, on the other hand, behave as expected with the hydrogen-disordered case (ice V) being more inhomogenously broadened. Furthermore, in all hydrogen-ordered forms (ice II and ice XIII), cross peaks could be identified in the anisotropic 2D IR spectrum, whose signs reveal the relative direction of the corresponding excitonic states. Published by AIP Publishing.
Additional indexing
Item Type: | Journal Article, refereed, original work |
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Communities & Collections: | 07 Faculty of Science > Department of Chemistry |
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Dewey Decimal Classification: | 540 Chemistry |
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Scopus Subject Areas: | Physical Sciences > General Physics and Astronomy
Physical Sciences > Physical and Theoretical Chemistry |
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Language: | English |
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Date: | 14 October 2017 |
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Deposited On: | 09 Mar 2018 12:54 |
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Last Modified: | 26 Jan 2022 16:26 |
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Publisher: | American Institute of Physics |
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ISSN: | 0021-9606 |
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Funders: | Swiss National Science Foundation (SNF) through the NCCR MUST, Royal Society International Exchanges Scheme Grant, Royal Society University Research Fellowship, Leverhulme Research Grant |
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OA Status: | Green |
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Publisher DOI: | https://doi.org/10.1063/1.4993952 |
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Project Information: | - : FunderSNSF
- : Grant ID
- : Project TitleSwiss National Science Foundation (SNF) through the NCCR MUST
- : Funder
- : Grant ID
- : Project TitleRoyal Society International Exchanges Scheme Grant
- : Funder
- : Grant ID
- : Project TitleRoyal Society University Research Fellowship
- : Funder
- : Grant ID
- : Project TitleLeverhulme Research Grant
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